Which number is prime?

A : 8

B : 6

C : 13

D : 10

C : 13

8 is not a prime number since it's dividable by multiple numbers. For example 2 (4), 1 (8)

6 is not a prime number since it's dividable by 3 (2), 1 (6)

13 is a prime number because it's only dividable by itself.

10 is not a prime number because it can be divided by 5 (2), 1 (10)

So only 13 matches as a prime number.