The first one seems the most correct
The myelin sheath covers most of the axon. It is important because it helps to protect the axon and speed up the neuron firing process by decreasing the amount of time in the axon.
A dominant trait will mask a recessive trait.
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.
Answer:
The largest internal organ in the body is the liver by mass
