A particle projected vertically upward reaches, at the end of t seconds, an elevation of s feet where s=160t−16t2. The highest elevation is:<spanclass=′latex−bold′>(A)</span>800<spanclass=′latex−bold′>(B)</span>640<spanclass=′latex−bold′>(C)</span>400<spanclass=′latex−bold′>(D)</span>320<spanclass=′latex−bold′>(E)</span>160