Why Is the Change in Sensitivity of Female Midshipman Fish

Why is the change in sensitivity of female midshipman fish to the "songs" produced by males of their species a proximate example of stimulus filtering?

A) In the seasons when female midshipman fish lack a sensitivity to high frequency elements, they cannot easily detect the sounds that they are able to hear in the summer breeding season.
B) These changes in sensitivity are linked to the genetically determined innate releasing mechanisms of the fish.
C) The changes in sensitivity to high frequency sounds occur when it is adaptive for females to hear the songs of males eager to spawn with females.
D) The greater sensitivity to high frequency sounds enables females to hear sounds that require a different proximate mechanism than the mechanism that enables females to hear lower frequency sound.