Answer:
The answer is the quadriceps.
Explanation:
The hamstring, located between the hip and the knee joint, is one of the biggest muscles in the human body and one of the three posterior thigh muscles. In order to properly stretch the hamstring so as not to cause any injuries, because the hamstring is one of the muscles most susceptible to injury, the person needs to stretch their quadriceps knee extension during the active supine biceps femoris stretch.
I hope this answer helps.
