The function f(x) = −x2 − 9x + 10 shows the relationship between the vertical distance of a diver from a pool's surface f(x), in feet, and the horizontal distance x, in feet, of a diver from the diving board. what is a zero of f(x), and what does it represent?

a: x = 1; the diver jumps in the pool at 1 foot per second
b: x = 10; the diver jumps in the pool at 10 feet per second
c: x = 1; the diver hits the water 1 foot away horizontally from the board
d: x = 10; the diver hits the water 10 feet away horizontally from the board