A rock is thrown from one side of a river to another. The function h (t) = -16t^2 + 12t + 3 gives the height in inches of the rock t seconds after it has been thrown. What does 0 = -16t^2 + 12t + 3 represent in the context of this problem?
a. It represents the maximum height of the rocks as it is thrown from one side of the river to the other.
b. It represents the height of the rock 0 seconds after it was thrown.
c. It represents the time it takes for the rock to cross the river.
d. It represents the time it takes for the height of the rock to be 0 inches above the ground.