If n is a natural number, then 6n^2 + 6n is always divisible by?	Choose one.
A) 6 only  B) 6 and 12 both  C) 12 only  D) 18 only  E) 20 only
6n^2 + 6n = 6n(n+1), which is always divisible by 6 and 12 both, since n(n+1) is always even.   Answer is 6 and 12 both
<result>B</result>
If n is a natural number, then 6n^2 + 6n is always divisible by?