Solve the Problem $$s ( t ) = - 16 t ^ { 2 } + 96 t$$

Multiple Choice

Solve the problem.
-An explosion causes debris to rise vertically with an initial velocity of 96 feet per second. The function $$s ( t ) = - 16 t ^ { 2 } + 96 t$$ describes the height of the debris above the ground, s(t) , in feet, t seconds after the explosion. What is the instantaneous speed of the debris 4.8 second(s) after the explosion?

A) 153.6 ft/sec
B) -57.6 ft/sec
C) 57.6 ft/sec
D) -153.6 ft/sec