What are the reasons for the ratings of Crysis 2

The ESRB rating of Mature means they think nobody under 17 should play the game. It is rated Mature because of blood, partial nudity, strong language and blood. The blood and violence is because it is a war game. I don't know why it is rated for partial nudity, I didn't see any nudity when I was playing. It is rated for language because the soldiers sometimes yell bad words at the aliens.