Answer: C. The drone is on the ground at 0 and 4 seconds.
Step-by-step explanation:
Here the function that shows the height of the drone,
h(t) = -16(t-2)^2+64
Where t is the time in seconds.
Since, the drone is ground when, h(t) = 0
-16(t-2)^2+64=0
-16(t-2)^2 = -64 (by subtracting 64 from both sides 64)
(t-2)^2 = 4 (dividing both sides by -16 )
t^2-4t+4= 4
t^2-4t= 0 (by subtracting 4 from both sides)
t(t-4)= 0
⇒ t = 0 or t = 4
Thus, Option C is correct.