Male tungara frogs have a call that contains a chuck sound that is attractive to tungara frog ...

Male tungara frogs have a call that contains a chuck sound that is attractive to tungara frog females, but that is absent from the calls of males in closely related species.
 
  Which of the following experiments could you use to test the sensory bias model as an explanation for the evolution of the chuck sound?
  a. test the attractiveness of recorded tungara male calls from which you have digitally removed the chuck on conspecific females
  b. test the attractiveness of heterospecific male calls on tungara frog females
  c. test the attractiveness of tungara frog calls with chuck on con- and heter-ospecific females
  d. test the attractiveness of tungara frog calls with chuck on females of an unrelated species that also has male calls with a similar chuck sound