The correct answer is A.
Pain receptors also called nociceptors are sensory receptors that detect signals from damaged tissues or the threat of damage. The nociceptors also indirectly respond to chemicals released from damaged tissue.
Pain is referred to as nociceptive. In latin, the word nocer means to injure or to hurt. Nociceptive means sensitive to noxious stimuli. Noxius stimuli are stimuli that are implicated in tissue damage and they activate nociceptors( pain receptors)
Nociceptors are free (bare) nerve endings found in the skin, muscle, joints, bone and viscera.
