If x and y are different integers, both divisible by 6, then which is not necessarily true?
Choose the correct choice from the following:
A) x^2 + y^2 is divisible by 6 B) x - y is divisible by 6 C) xy is divisible by 6 D) x + y is divisible by 6 E) x + y is divisible by 12
Let x = 6k and let y = 6j.   Then x+y = 6(k+j) and k+j could be even or odd.   Thus 6(k+j) is not necessarily divisible by 12.   The answer is x + y is divisible by 12.
<result>E</result>
If x and y are different integers, both divisible by 6, then which is not necessarily true?