If n is a positive integer and n^2 is divisible by 200, then what is the largest positive integer that must divide n?  Choose the correct answer.
A) 10 B) 15 C) 20 D) 36 E) 50

Rationale: 200 = 2 ^ 3 * 5 ^ 2 if 200 divides n ^ 2 , then n must be divisible by 2 ^ 2 * 5 = 20 the answer is c .
Answer: C