At a Time T Seconds After an Object Is Tossed $s = 320 t - 16 t ^ { 2 }$

Multiple Choice

At a time t seconds after an object is tossed vertically upward, it reaches a height s in feet given by the equation: $s = 320 t - 16 t ^ { 2 }$
In how many seconds does the object reach its maximum height?

A) 800 sec
B) 1,600 sec
C) 10 sec
D) 5 sec