A rock is thrown from the edge of a cliff that is level with the surrounding ground. Its initial speed is 25m/s and the launch angle is 60∘ above the horizontal. Neglecting air resistance and using g=9.8m/s2, what horizontal distance does the rock travel before landing at the same elevation from which it was thrown?
a) 64m
b) 55m
c) 32m
d) 28m