The correct option is C 15
To solve this problem, first we have to break down the numbers into their prime factors.
The prime factorization of 50 is:
2 × 5 × 5
The prime factorization of 75 is:
3 × 5 × 5
Thus, the common divisors are :
5 and 5 × 5.
Additionally, the greatest common factor is 25.
Hence, 15 is not a common divisor.