Question

which of the following is an example of a stretch reflex?
when the doctor strikes your knee with a rubber hammer.
when you elicit a fear response to an unconditioned stimulus.
when you have a cold glass of water after a walk.
when you practice singing high notes.

Explanation:

The stretch reflex is a muscle contraction in response to stretching within the muscle. When a doctor strikes the knee with a rubber - hammer, it stretches the patellar tendon, triggering the stretch reflex which causes the lower leg to kick forward. The other options do not involve muscle - stretching related reflex actions.

Answer:

When the doctor strikes your knee with a rubber hammer.