Which of the following statements is true of stress and the immune system? a) Unlike the immune system, the central nervous system possesses "motor" elements, which carry out an appropriate response b)Unlike the central nervous system, the immune system possesses "sensory" elements, which receive information from the environment and other parts of the body. c) Corticotropin-releasing hormone is shared by the central nervous system and the immune system, uniting the stress and immune responses