Amolecule is: a. a mixture of various components that can vary b. a combination of many atoms that will have different ratios c. a combination of one or more atoms that will have a fixed ratio of its components

A molecule is: a combination of one or more atoms that will have a fixed ratio of its components 

The motor neurons could be severed which would inhibit the passing of electrical signals to the muscles. This is known as paralysis. It can be caused by severe spinal trauma, electric shock, or other forms of extreme physical or psychological stress.