Which of the following statements is true about movement of the forearm? In

A.

bending the arm, the biceps relax and the triceps contract

B.

bending the arm, the biceps contract and the triceps relax

C.

straightening the arm the biceps contract and the triceps relax

D.

straightening the arm, both biceps and triceps contract

Correct answer is B

To bend the arm, the biceps contracts and pulls on the radius. Simultaneously, the triceps relaxes.