A math student made the following conjecture:

When you add a multiple of 5 and a multiple of 8, the answer is a multiple of 5.

Which of the following numbers can be used as a counterexample to the conjecture?

A. 80 + 8 = 88

B. 16 + 16= 32

C. 10 + 5 = 15

D. 10 + 40 = 50