A rocket is launched from the ground. The function h(t)= -4.9t^2 +180t models the height of a rocket launcher from the ground t seconds after it is launched. If all other factors remain the same, which of the following function models the height of a rocket above the ground after t seconds if it is launched from a platform 100 feet in the air?
(1) h(t) = -4.9t^2 +280t
(2) h(t) = -4.9t^2 +180t -100
(3) h(t) = -4.9t^2 +180t +100
(4) h(t) = -4.9t^2 +180 (t+100)