What is the smallest positive integer K such that the product of 1575 x K is a perfect square? Choose the correct choice:
A) 7
B) 9
C) 15
D) 25
E) 63

Rationale: "perfect square , is just an integer that can be written as the square of some other integer . for example 16 = 4 ^ 2 , is a perfect square . now , 1575 = 3 ^ 2 * 5 ^ 2 * 7 , so if k = 7 then 1575 k = ( 3 * 5 * 7 ) ^ 2 , which is a perfect square ( basically the least positive value of k must complete only the power of 7 to even power as powers of other primes are already even ) . answer : a ."
Answer: A