The correct option is C 31 and 37
Composite numbers are numbers which have more than 2 factors.
30, 32, 33, 34, 35, 36, 38, 39 have more than two factors.
So, 30, 32, 33, 34, 35, 36, 38, 39 are composites among the given numbers.
whereas, 31 and 37 have only 1 and themselves as factors.
so, 31 and 37 are prime numbers among the given set of numbers.