How many perfect squares are divisors of the product 1!⋅2!⋅3!⋯9!?
<spanclass=′latex−bold′>(A)</span>504<spanclass=′latex−bold′>(B)</span>672<spanclass=′latex−bold′>(C)</span>864<spanclass=′latex−bold′>(D)</span>936<spanclass=′latex−bold′>(E)</span>1008