Solve the Problem $78.4 \mathrm{~m}$ High as It Is Falling, Its Height Is Given by When

Multiple Choice

Solve the problem. Round your answer to the nearest tenth, when appropriate.
-A rock falls from a tower that is $78.4 \mathrm{~m}$ high. As it is falling, its height is given by the formula $\mathrm{h}=78.4-4.9 \mathrm{t}^{2}$ . How many seconds will it take for the rock to hit the ground $(\mathrm{h}=0)$ ?

A) $8.9 \mathrm{sec}$
B) $1254.4 \mathrm{sec}$
C) $8.6 \mathrm{sec}$
D) $4 \mathrm{sec}$