Water coming out from a fountain is modeled by the function f(x) = -x2 + 6x + 6 where f(x) represents the height, in feet, of the water from the fountain at different times x, in seconds.

a. the water travels an average distance of 4 feet from 2 seconds to 5 seconds.

b. the water travels an average distance of 1 foot from 2 seconds to 5 seconds.

c. the water falls down with an average speed of 2 feet per second from 2 seconds to 5 seconds.

d. the water falls down with an average speed of 1 foot per second from 2 seconds to 5 seconds.