252 can be expressed as a product of primes as_______________?

A. 2 * 2 * 3 * 3 * 7
B. 2 * 2 * 2 * 3 * 7
C. 3 * 3 * 3 * 3 * 7
D. 2 * 3 * 3 * 3 * 7