For how many positive integers n less than or equal to 24 is n! evenly divisible by 1 \plus{} 2 \plus{} \dots \plus{} n?
<spanclass=′latex−bold′>(A)</span>8<spanclass=′latex−bold′>(B)</span>12<spanclass=′latex−bold′>(C)</span>16<spanclass=′latex−bold′>(D)</span>17<spanclass=′latex−bold′>(E)</span>21