Answer:
D
Step-by-step explanation:
All are composite.
57 can be divisible by 19 etc.
21 is divisible by 7 and 3 and etc.
and its given that 46 is composite because its even. (divisible by 2)
With 21, the factors are 3 and 7
With 46, it's an even number so it's composite.
With 57, the factors are 3 and 19
