a)the frequency of a sound wave
b)the rate at which a wave’s energy flows through a given area
c)the amplitude of a sound wave
d)the physical response to the intensity of sound, modified by physical factors
D is the best answer. C is somewhat true, increasing the amplitude of a wave will make it louder, but loudness depends on the listener. To a person hard of hearing, a given amplitude will sound quieter than for a normal hearing person.
