Final answer:
During quiet expiration, the diaphragm and external intercostal muscles relax, allowing for passive exhalation without active contraction of the muscles. Therefore, the correct answer to which muscles contract during quiet expiration is 'd) none of the above'.
Step-by-step explanation:
The student's question pertains to which muscles contract during quiet expiration. During quiet expiration, such as when the body is at rest, the process is mostly passive, which means that it generally does not require active muscle contraction. The muscles involved in the active process of breathing include the diaphragm and intercostal muscles. During quiet expiration, the diaphragm relaxes, moving upward, and the ribs moved inward as the external intercostal muscles relax, leading to a decrease in thoracic volume and the passive expulsion of air. The internal intercostal muscles can be involved during forced exhalation as they help constrict the rib cage, but during quiet expiration, they are not actively contracting.
To answer the student's question: Which of the following muscles contract(s) during quiet expiration?
a) diaphragm
b) internal intercostals
c) external intercostals
d) none of the above
e) all of the above
The correct answer is d) none of the above.