Which one of the following explains the role of an antagonist in muscle movement?The antagonist can also be called the prime moverThe antagonist contracts and shortensThe antagonist relaxes and lengthensThe antagonist causes the movement to occur

To answer the question step by step, let's analyze each option provided:

1. "The antagonist can also be called the prime mover":

   • This statement is incorrect. The prime mover, or agonist, is the muscle that is primarily responsible for generating a specific movement. The antagonist, on the other hand, opposes the action of the agonist.

2. "The antagonist contracts and shortens":

   • This statement is also incorrect. When the agonist muscle contracts and shortens to produce movement, the antagonist muscle must do the opposite to allow the movement to occur.

3. "The antagonist relaxes and lengthens":

   • This statement is correct. During muscle movement, the antagonist muscle relaxes and lengthens to allow the agonist muscle to contract and shorten, facilitating the movement.

4. "The antagonist causes the movement to occur":

   • This statement is incorrect. The antagonist does not cause the movement; rather, it opposes the movement. The agonist is responsible for causing the movement.

Therefore, the correct explanation of the role of an antagonist in muscle movement is: "The antagonist relaxes and lengthens."