Question ID:PT86 S1 Q22 Passage:Although severing a motor nerve kills part of the nerve, it can regenerate, growing about 1 millimeter per day from the point of damage toward the muscle the nerve controlled. So, for example, a severed motor nerve that controlled a hand muscle requires a much longer time to regenerate if that nerve is severed at the shoulder rather than at the wrist. Furthermore, the growing cells require the original nerve sheath to guide them to the area that has lost function, but that sheath begins to disintegrate after about three months unless there is living nerve tissue within it.  Stem:The statements above, if true, most strongly support which one of the following? Correct Answer Choice:DChoice A:Doubling the speed at which new nerve cells grow will double the likelihood that a severed motor nerve will reach the muscle it had controlled.  Choice B:It is sometimes possible, once a nerve sheath has begun to disintegrate, to reverse or slow the process of disintegration. Choice C:If a severed motor nerve does not regenerate successfully within three months after being severed, functioning cannot be restored to the muscle that the nerve had controlled. Choice D:If living nerve tissue could be implanted and sustained within the original sheath of a severed motor nerve, the likelihood that the nerve will regenerate would increase in some cases. Choice E:Without surgical intervention, a muscle that has lost function because of a severed motor nerve is unlikely to regain that function.