Question

Read the following scenario to answer the following questions.
Yawning is a reflexive action that is often associated with sleepiness. When a person yawns, the mouth opens, and a longer than normal breath of air is inhaled, followed by a longer than normal exhalation. Hypothesizing that yawning has a regulatory mechanism similar to breathing, scientists conducted an experiment on college students to test the effect of ambient carbon dioxide levels on yawning.
When a person exhales to complete a yawn, what happens?
A) The rib muscles contract.
B) The diaphragm contracts.
C) The rib muscles act in the same way that they do in an inhalation.
D) The diaphragm relaxes.

Answer

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