Let P(x)=1−x+x2−x3+⋯+x18−x19 and Q(x)=P(x−1). What is the coefficient of x2 in polynomial Q?<spanclass=′latex−bold′>(A)</span>840<spanclass=′latex−bold′>(B)</span>816<spanclass=′latex−bold′>(C)</span>969<spanclass=′latex−bold′>(D)</span>1020<spanclass=′latex−bold′>(E)</span>1140