Answer: B

Given the definition of h(n), h(10) is the sum of the even integers between 2 and 10 inclusive, and h(18) is the sum of the even integers between 2 and 18 inclusive.

For each, use a trick to get to the sum sooner. The sum of the numbers is the average times the number of terms. The average is simply the midpoint between the two endpoints. So for 2 ... 10, the midpoint is 6. There are 5 evens between 2 and 10 inclusive, so the sum is 5*6 = 30.

By the same reasoning, the midpoint of 2 ... 18 is 10, and there are 9 evens in that range, so the sum is 10*9 = 90. Divide 90 by 30, and the result is 3, choice (B).