Jyp’s A2K survival show (this may sound stupid but i’m so confused)

So I know that everyone that auditions goes through 2 rounds before they perform in front of JYP, but why do some dance and sing while others only sing or maybe just dance? Why don’t they all do both?? Plus why do they all get pendants like I get they have to audition 3 times basically but how do they all end up with pendants???? And please don’t call me stupid J already know I am i just need someone to explain to me 😭🙏