A steel ball is released from rest at a height $h$ above the ground. It reaches the ground after a time $t$. The experiment is carried out again for several different heights. The graph shows how $h$ varies with $t^2$ for the ball. The gradient of the graph is $G$. Which expression gives the acceleration of the ball?
- A$\frac{G}{2}$
- B$G$
- C$2G$
- D$G^2$