'X Factor' judges send four hopefuls home

• Top 16 becomes Top 12
• Who had to sing for survival?
• No nipple action Thursday from Khloe Kardashian Odom

On the second live episode of The X Factor, host Khloe Kardashian Odom wore a shorter outfit, but a less sheer one. No nipples on parade tonight as she sported a short-sleeve blue leather dress. Tweeted sister Kim: "Seriously my sister @KhloeKardashian looks so stunning on@XFactorUSA! love her hair,make up, that blue dress, everything!"

With that news flash out of the way, we can tell you Thursday's show was focused on mentors L.A. Reid, Demi Lovato, Simon Cowell and Britney Spears whittling the acts down from 16 to 12.

"They're like my children, so it's going to be very hard to choose which one of my children will go home," Britney said.

Khloe, yelling over the annoying constant crowd noise, asked Simon whether it would be easy for him tonight. His response, "Sorry?"

Each mentor picked two of their four acts to advance. Then the remaining two acts in each category had to sing for survival.

First up: Young Adults (ages 17-24). "Overall, I was really proud of my acts," said Demi, before putting Jennel Garcia and Paige Thomas, who rocked a gigantic, gorgeous hat, through to the Final 12.

Backstage, a weeping Jennel told Khloe, "I'm so happy for myself." While Paige said, "I can't put into words what this means."

Singing for survival: Cece Frey and Willie Jones.

A toned-down Cece stood still at the front of the stage and belted out Out Here On My Own from Fame. L.A. said, "You just saved yourself." Britney: "It was very powerful." Cece stood crying on stage. Simon told her he didn't understand why she didn't do something like this last night.

Willie also scaled back his performance, losing the dancers he had from the night before and offering a slow and steady rendition of Nat King Cole's You Don't Know Me. "That was good," said L.A. Britney said he has a "unique quality" but isn't sure where he fits in. Simon says his mentor (Demi) doesn't understand what he needs to do with his voice.

Demi's decision: Cece moves on. Willie goes home. "I just think it's not your time right now," said Demi, who was wearing a short shirtdress with the buttons opened to reveal her brown bra. She gave Willie a hug.

Second group: Over 25s. L.A. Reid said he thought all of his acts "did great," except he regretted Jason Brock's song choice. The two acts he put through to the Top 12: tattooed rocker Vino Alan and country dude Tate Stevens. "This is what you work for all your life," Vino told co-host Mario Lopez backstage. Tate said his kids were proud of him.

Singing for survival: David Correy and Jason Brock.

David opted for a soulful version of Kelly Clarkson's Since U Been Gone. The crowd, which never shuts up, really went wild for it. Said Britney, "You blew us away." Demi didn't like it; she felt it was "way too forced." Simon thought it was a good song choice, but felt it was "a little melodramatic."

Jason sang Whitney Houston's One Moment in Time, smiling at the mentors as he yelled the high notes. Britney said, "Today you turned me into a fan." Demi said, "There's something really genuine in you, behind your eyes" (her favorite phrase). Simon had a "slight problem —- you're asking me to choose between two horses last in a race." He doesn't believe either one can go on to win the competition.

L.A.'s decision: To Simon, he said, "That was really mean," and went on to defend both singers as "really good." He felt it came down to "Mr. Entertainment vs. The Star." His decision: "Mr. Entertainment" Jason Brock moves on. David Correy goes home. "Not a popular decision here tonight," noted Mario. "I promise you, this is not going to be the last time you see my face," David told the audience, and he thanked L.A. for mentoring him.

Next group: Teens. "Overall, I'm so proud of all of them," said mama Britney. But she put through Beatrice Miller and Carly Rose Sonenclar. "I feel amazing!" Beatrice told Mario Lopez backstage. She added she felt "weird" that fans were yelling for Carly but Britney said Beatrice's name first.

Singing for survival: Diamond White and Arin Ray.

Arin poured his heart into Whitney Houston's I Look To You. L.A. loved it. "Every time you step behind that mic I'm impressed." Demi agreed, adding, "It would be a shame to see you go." Simon raved: "That was a great performance."

Diamond also poured her heart into her song —- Elton John's Sorry Seems To Be The Hardest Word. "You are a sensational vocalist," said L.A. No matter what happens, he said, "you have a real future in this business." Demi said, "I like the soul and fire behind your eyes." Simon said he didn't envy Britney, having to decide between the two great acts. He first thought Arin should go through, but now thinks Diamond should advance.

"This is like the hardest decision ever," said Brit Brit. Finally, with a pained look on her face, she sent Diamond home. Both Diamond's and Arin's jaws dropped. "I'm still going to keep smiling. I still love you, Britney," said a gracious Diamond.

Final category: Groups. "Even up until five minutes ago, I hadn't made my mind up," swore Simon, then announced that cute boy band Emblem3 was the first act moving on to the Top 12. Second act advancing: Rap group Lyric 145.

Singing for survival: Sister C and 1432.

Sister C, made up of three sisters from Austin, sang When I Look At You. The camera cut to a shot of Simon taking a drink from his Pepsi cup. L.A. liked the song choice. Britney was "pleasantly surprised" by the performance. "I feel like you guys really want this and have the eye of the tiger. ... And that's really refreshing." Demi said she thought it would be a mistake for them to be kicked out of the competition.

1432, five teen girls who only recently became a group, showcased each of their beautiful voices in Demi Lovato's Skyscraper. L.A. liked it. Britney said they made her a believer. Demi said, "You did better than the original singer."

Decision time. Mario asked Simon Cowell which group he was sending home. "Actually, let me make this more positive because I'd rather end on a positive," said Simon. "I'd rather say the group I'm going to save."

No, insisted Mario. "I'm sorry, we need the name of the act you are sending home."

"I like happy news," whined Simon.

"We all like happy news, but unfortunately we're all going to have to deal with a little bit of sad news at the moment," said Mario.

Simon sent home Sister C. Landing the final spot in the Top 12: 1432. But before the show closed, Simon said he hates the name of the group, 1432. He's going to put out a call to the public to submit a new name for the group.