Find All Fixed Points for the Function by Setting the Function

Multiple Choice

Find all fixed points for the function by setting the function equal to x and solving the resulting equation for x.
-A rock falls from a tower that is 464 feet high. As it is falling, its height is given by the function $h ( t ) = - 16 t ^ { 2 } + 464 t$

A) 21.2 seconds
B) 5.4 seconds
C) 21.5 seconds
D) 13,456 seconds