well theory is ranked second highest in certainty in scientific nomenclature. theory dictates it is more certain of a principle than a hypothesis yet not concrete enough to be a law. examples are the theory of evolution versus the law of gravity
Afferent nerve fibers carry signals from the somatic receptors to the posterior horn of the spinal cord or to the brainstem. So i beleive it is 4 but not too sure. Hope this helped a bit (:
