The correct answer is d.
The equation h(t) = -16t^2 + 36 gives the height of the object above the ground at time t. So, h(1.5) gives the height of the object 1.5 seconds after it is dropped. If h(1.5) = 0, it means the height of the object is zero, or it has hit the ground at that time. Therefore, the best description of the meaning of h(1.5) = 0 in terms of the context is that the object hits the ground 1.5 seconds after it is dropped.