One theory of pitch perception is the theory, which suggests that the rate at which neurons in the ear fire produce different pitches. this theory is particularly effective at explaining humans' perception of lower pitches.
a. place
b. frequency
c. volley
d. opponent-process

b. frequency

Explanation:

The frequency theory states that the human ear allows you to hear the different frequencies that are generated by the waves of sound, this is why we can hear different sounds and pitches, humans across the story have had the ability to hear lower pitches because that is the main pitch in which we humans speak, so te human ear adapted to hear better and pay closer attention to those pitches, so the frequency theory explains why humans can hear lower pitches.