A volleyball is hit upward from a height of 4 feet at an initial speed of 20 feet per second. As the volleyball travels, Earth’s gravity slows it down. The height of an object dropped from a height of 4 feet is given by h(t)=−16t^2+4.

The distance in feet traveled by an object at a constant speed of 20 feet per second is given by d(t)=20t.

These two functions can be combined to build a new function, f, that models the height of the volleyball as a function of time in t seconds.

Which choice shows how to combine h and d to build f?

A. f(t)=h(t)−d(t)

f(t)=−16t^2−20t+4

B. f(t)=d(t)−h(t)

f(t)=16t^2+20t−4

C. f(t)=h(t)⋅d(t)

f(t)=(−16t^2+4)(20t)

D. f(t)=h(t)+d(t)

f(t)=−16t^2+20t+4