Final answer:
The statement that does NOT describe tetanus is that the muscle relaxes fully between contractions. Tetanus is characterized by sustained muscle contraction without full relaxation due to continuous high calcium ion concentration. The correct option is A.
Step-by-step explanation:
The student's question was: Which of the following does NOT describe tetanus? The answer is A. The muscle relaxes fully between contractions.
During tetanus, a high concentration of Ca++ ions in the sarcoplasm enables virtually all of the sarcomeres in muscle fibers to form cross-bridges and generate sustained contraction, without fully relaxing in between.
This can be referred to as complete tetanus where contractions fuse and become continuous, in contrast to incomplete tetanus where there are quick cycles of contraction with only a short relaxation phase.
The statement that the muscle relaxes fully between contractions is incorrect in reference to tetanus. The correct option is A.