What does tension mean?

Muscle fiber generates tension during the action of actin and myosin cross-bridge cycling.

Ask yourself, when is there tension in the muscle? When you flex, correct? In what position is the myosin and actin when flexing

Isn't there the most tension when the myosin and actin are pulled closest together? So why doesn't D have the greatest tension?

The shortening of the fibers creates mechanical force, or muscle tension. Whether the muscle itself changes length (same-force or isotonic contraction) or not (same-length or isometric contraction) depends upon the load attached to the muscle. For example, your biceps muscle is attached to your shoulder blade at one end and to your ulna in your forearm at the other end. When the biceps contracts, it shortens and pulls the ulna toward the shoulder blade (the ulna is attached to the elbow joint). This movement allows you to lift your forearm and a given load. In contrast, if you are carrying a heavy load, such as a full suitcase, that makes you unable to lift your forearm, then the biceps does not shorten significantly. But the force that the muscle generates is helping you carry the suitcase.

Thanks, I follow what you are saying, so why is D not the answer for having the greatest tension in my question?

that's strange. okay, in a relaxed muscle actin and myosin lie side by side and the h zones and i bands are at maximum width. i suppose at contraction, when the i bands get very narrow, tension decreases. there must be a physics reason why, but i too am not understanding the corelation.

what textbook is this from?

Life 9th Edition

http://courses.bfwpub.com/life9e.php

Stupid e-texts...:/