Water coming out from a fountain is modeled by the function f(x)= -x^2+5x+4 where f(x) represents the height, in feet, of the water from the fountain at different times x, in seconds. what does the average rate of change of f(x) from x=3 to x=5 represent?

a. the water falls down with an average speed of 3 ft./s from three seconds to five seconds.
b. the water falls down with an average speed of 5 ft./s from three seconds to five seconds.
c. the water travels an average distance of 3 feet from 3 seconds to 5 seconds.
d. the water travels an average distance of 5 feet from 3 seconds to 5 seconds.