Final answer:
Motor TENS targets the gate control theory of pain control by stimulating nerve fibers and modulating pain signals through the opening and closing of neural gates in the spinal cord.
Step-by-step explanation:
The pain-control theory targeted by motor TENS is the gate control theory. Motor TENS (transcutaneous electrical nerve stimulation) uses electrical impulses to stimulate nerve fibers and target the gate control system of pain perception. According to the gate control theory, pain signals can be modulated and controlled by opening and closing neural gates in the spinal cord.