A person walking across a bridge accidentally drops an orange into the river below from a height of 40 feet. The function h = −16t^2 + 40 gives the orange’s approximate height h above the water, in feet, after t seconds. In how many seconds will the orange hit the water?
a. 1.6 seconds
b. 0.6 seconds
c. 2.3 seconds
d. 3 seconds