Good quiz, nice mixture of pictures: I think 'Ear' should be enough for the answer, ear drum is such a small part of what is shown. Ear bones, Eustachian Tube, Ear Canal etc.
I agree with Malbaby. I also think the exponent is hard to understand without a circle around the exponent- especially because the first equation has no exponent, and exponent is a quantity, not a function.