A model jet is fired up in the air from a 20-foot platform with an initial upward velocity of 68 feet per second. The height of the jet above ground after t seconds is given by the equation h=-16t^2+68t+20, where h is the height of the jet in feet and t is the time in seconds since it is launched. What is the maximum height the jet reaches, to the nearest foot?
A.
92 feet
B.
20 feet
C.
68 feet
D.
16 feet