Answer: D. Mechanoreceptors
Explanation: Sound comes in the form of soundwaves that travel through the environment. These waves enter our ear canal, go through the eardrum, and go into the cochlea. The cochlea is a snail shaped cavity found in the inner ear that contains hair cells. These cells move back in forth in response to soundwaves, transducing the sound waves into a neural signal that we can process as hearing and sound.
These hair cells are considered mechanoreceptors, which are receptors triggered by physical movement. After all, the hair cells are moved by physical soundwaves flowing through the cochlea. None of the other receptors accurately describe what hair cells are.
Thermoreceptors detect changes in temperature. These receptors are responsible for our sense of touch and tactile sensation, not hearing.
Photoreceptors detect and gather light. These receptors are mainly responsible for our vision, but play no role in helping us hear.
Chemoreceptors are responsible for detecting specific molecules and chemicals. These receptors are mainly used in our sense of smell and taste, but play no role in hearing. Thus, only choice d is the correct answer.