The correct answer is letter A. Pain receptor - tissue injury. Nociception refers to the processing of harmful stimuli in the nervous system. The nociceptors are also known as "Pain receptor" that responds only to tissue damages cause by either mechanical, thermal stimulation.
The answer which accurately pairs the type of receptor to the stimuli in which it responds would be pain receptor - tissue injury - a.
When we're talking about pain receptors, we're talking about a kind of receptors which will detect signals in various ways from the damaged tissues that are considered to be threatened by immediate damage.
