Find the highest common factor of 36 and 84?	Choose the correct choice from the following choices.
A) 4	B) 6	C) 12	D) 18	E) none of these

Rationale: 36 = 2 ^ 2 * 3 ^ 2 ; 84 = 2 ^ 2 * 3 * 7 h . c . f = 2 ^ 2 * 3 = 12 . correct option : c
Answer: C