Akey hormone shared by the central nervous system and the immune system is which is produced in the hypothalamus and unites the stress and immune responses. oxytocin testosterone estrogen corticotropin-releasing hormone (crh)

The answer to this problem is the last item from the choices which is the "CHR" which stands for "CORTICOTROPIN-RELEASING HORMONE". This is a key hormone that is shared by the central nervous system and the immune system of the human's body commonly called as a corticotropin-releasing hormone. This is s peptide hormone involves in the stress response of a person.