I am pretty sure that if muscle cells failed to function properly the thing that would happen is being revealed by the first option : A. The muscles will not work. I choose this one because as you know muscles are made of muscle tissue and if cells fail it won't functionate at all.
Probably through a electron microscope either TEM or SEM. or possibly a picture through the microscope. I hope that helped.
I believe <u>B.) Analogous structures show that living in similar habitats doesn't lead to similar adaptations </u>is your right answer.
Earthworms have no special respiratory organs. Gases are exchanged through the moist skin and capillaries