SAT Math Practice Question

$$h(x)=-16 x^{2}+100 x+10$$The quadratic function above models the height above the ground $h$, in feet, of a projectile $x$ seconds after it had been launched vertically. If $y=h(x)$ is graphed in the $x y$-plane, which of the following represents the real-life meaning of the positive $x$-intercept of the graph?

1. A.The initial height of the projectile
2. B.The maximum height of the projectile
3. C.The time at which the projectile reaches its maximum height
4. D.The time at which the projectile hits the ground