Consider this living plant a system. To be alive, the plant needs energy. As a plant, it produces its own usable chemical energy
by photosynthesis and uses that same energy through cellular respiration. One output of photosynthesis is a critical reactant or input for respiration. That is
C. The gate-control theory. The gate control theory of pain states that non-painful inputs closes the nerve gates to painful input, which prevents pain sensation from traveling to the central nervous system.
