Okay. Spinal cells are the cells in the spinal cord. That answer doesn't make sense, because how do spinal cells in the spinal cord send messages? Doesn't make much sense, right? Therefore, B is eliminated. C is definitely eliminated, because muscles are not part of the nervous system at all, and you completely have control over them. Neutrinos has to do with physics, not the human body. Neurons are part of the nervous system, are made up of cells, and they have electrical impulses go through. Neurons is the only one that makes sense. The answer is A: neurons.
