For how many positive integers n does 1 \plus{} 2 \plus{} \cdots \plus{} n evenly divide from 6n?
<spanclass=′latex−bold′>(A)</span>3<spanclass=′latex−bold′>(B)</span>5<spanclass=′latex−bold′>(C)</span>7<spanclass=′latex−bold′>(D)</span>9<spanclass=′latex−bold′>(E)</span>11