Producers are typically plants, so I believe the correct answers would be 2, 3, 4.
The answer is outer hair cells can be seen near the center
of the basilar membrane where the hightest vibration takes place. The basilar membrane can be seen under the
inner hair cells, the movement of stereocilia and the resulting modulation
of their ionic currents is likely to be greater for outer hair cells than for
inner hair cells.
