Sharks have highly developed
thermoreceptors
photoreceptors
olfactory receptors
mechanoreceptors

olfactory receptors

Sharks have highly developed olfactory receptors. The olfactory receptors in animals allows them to sense the odor. Sharks have olfactory receptors more sensitive than humans. They have nostrils located on the underside of their snout, which they use for smelling not for breathing. The smell of the prey animal or the blood of any animal is detected by the shark with the help of these receptors.

the correct answer, according to e2020, is the second choice there is an occluded front in region a and a cold front in region b.

answer///unconditioned stimulus;