The correct option is C 3
The numbers which can be multiplied with some other number to get the given number are called the factors of that number.
Factors of 15:
1 × 15 = 15
3 × 5 = 15
5 × 3 = 15
15 × 1 = 15
1,3,5,15 are the factors of 15
∴ 3 is a factor of 15