If n is a positive integer, which of the following expressions must be a multiple of 6?

✓ Correct Answer: Option C

The product of three consecutive integers, n(n+1)(n+2), must always contain at least one multiple of 2 and at least one multiple of 3. Since 2 and 3 are prime, their product, 6, must divide the expression. Thus, n(n+1)(n+2) is always a multiple of 6.