Final answer:
To lift a weight, an isotonic muscle contraction with a force greater than the load is necessary, involving the shortening of the muscle fibers to generate sufficient tension. The correct option is B.
Step-by-step explanation:
For a weight to be lifted, an isotonic muscle contraction with a force greater than the load must occur. This type of contraction involves the shortening of muscle fibers (sarcomeres) as they generate enough muscle tension to move the load.
Isotonic contractions come in two forms: concentric, where the muscle shortens as it works against gravity or resistance (as when you lift a weight), and eccentric, where the muscle lengthens under tension (as when you lower a weight back down).
In contrast, an isometric contraction occurs when the muscle exerts force without changing length, which happens when the muscle tension is unable to move the load. Hence, the correct answer to the student's question is B. An isotonic muscle contraction with a force greater than the load. The correct option is B.