Why Is the Shape of the Basilar Membrane Important in Coding

Why is the shape of the basilar membrane important in coding the frequency of sounds?

A) It is not important.The shape of the membrane has no impact on the coding of sound frequency.
B) The fibers at the free end are longer than the fibers at the attached end,which means the longer fibers vibrate at a lower frequency than the shorter fibers.
C) The fibers at the free end are shorter than the fibers at the attached end,which means the shorter fibers vibrate at a lower frequency than the shorter fibers.
D) The fibers at the free end are shorter than the fibers at the attached end,which means the longer fibers vibrate at a higher frequency than the shorter fibers.