Final answer:
In Pavlov's terminology, the bright light shining into a person's eye is the unconditioned stimulus, and the resulting constriction of the pupil is the unconditioned response.
Step-by-step explanation:
If you shine a bright light directly into a person's eye, the pupil of the eye will reflexively constrict. Using Pavlov's terminology, the bright light would be termed the unconditioned stimulus, and the pupil constricting would be termed the unconditioned response. Therefore, the correct answer is a. unconditioned stimulus; unconditioned response.
The pupillary light reflex involves sensory input through the optic nerve and a motor response through the oculomotor nerve. When bright light hits the retina, it leads to a parasympathetic response through the oculomotor nerve, causing the pupil to constrict in order to limit the amount of light falling on the retina, which is an automatic reaction and does not require learning, thus classifying it as an unconditioned response to an unconditioned stimulus.