The sum of the numerical coefficients of all the terms in the expansion of (x−2y)18 is:<spanclass=′latex−bold′>(A)</span>0<spanclass=′latex−bold′>(B)</span>1<spanclass=′latex−bold′>(C)</span>19<spanclass=′latex−bold′>(D)</span>−1<spanclass=′latex−bold′>(E)</span>−19