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.
-The height, in feet, of a free-falling object t seconds after being dropped from an initial height s can be found using the function $h ( t ) = - 16 t ^ { 2 } + s$

A) 14.5 seconds
B) 15 seconds
C) 13 seconds
D) 12 seconds