Final answer:
The bent-over row employs the biceps to the greatest degree compared to the other exercises listed. The triceps brachii is responsible for extending the forearm, not the biceps. The force placed on the biceps during exercises is greater than the weight lifted, due to the principles of torque and lever arm distance from the elbow.
Step-by-step explanation:
The exercise which employs the biceps to the greatest degree is the C. Bent-over row. During this exercise, the biceps brachii muscle is heavily involved in the elbow flexion part of the rowing motion. In the other exercises listed, the biceps also play a role, but not to the same extent as in the bent-over row. The lat pulldown is primarily a back exercise targeting the latissimus dorsi, the deadlift is a full-body strength exercise that involves multiple muscle groups and is not bicep-focused, and while the pull-up also uses the biceps, it emphasizes the back muscles more significantly.
Extension of the forearm is achieved by the triceps brachii muscle. Therefore, the answer to which muscle extends the forearm is B. triceps brachii. The biceps help in the contraction and flexion of the arm, showing an isotonic contraction, which is a movement where the muscle changes length as it contracts and causes movement of a body part.
When examining the force placed on the bicep muscle during an exercise like bicep curls, due to the principles of torque, the force on the biceps is greater than the weight being lifted. This difference in force is due to the lever arm distances from the pivot point, which is the elbow in this case.