According to frequency theory: a. most sound waves are a complex mixture of many frequencies. b high-frequency sounds trigger a wave of activity that peaks near the beginning of the basilar membrane. c the rate at which impulses travel up the auditory nerve matches the frequency of the tone being heard. d frequent or prolonged stimulation of a sensory receptor causes that receptor to become less sensitive. e we hear different pitches because different sound waves cause different parts of the nerve cells in the cochlea to fire.

According to frequency theory the rate at which impulses travel up the auditory nerve matches the frequency of the tone being heard.

Option c

Explanation:

The frequency theory says that we hear sounds, there would be pulses which travel through the auditory nerve. It carries sound information to process the brain and pulse rate matches with frequency of heard tone.

According to the frequency theory the pitch can be sensed. The theory states that every tone has a wavelength of its own. This wavelength identical to the electrical impulse that is transmitted through the auditory nerve.  

Example: Tone of 500Hz is equal to 500 electrical impulses transmitted through the auditory nerve in a given period of time.