If n is a positive integer and n^2 is divisible by 450, then what is the largest positive integer that must divide n?  Pick:  A) 10  B) 20  C) 30  D) 40  E) 50

Rationale: "450 = 2 * 3 ^ 2 * 5 ^ 2 if 450 divides n ^ 2 , then n must be divisible by 2 * 3 * 5 = 30 the answer is c ."
Answer: C