Scenario Yawning Is a Reflexive Action That Is Often Associated with with Sleepiness

Multiple Choice

Scenario
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 existing carbon dioxide levels on yawning.
-What finding would be considered support for the hypothesis tested by the scientists?

A) College students produce more carbon dioxide when they yawn more frequently.
B) College students yawn with the same frequency regardless of carbon dioxide levels.
C) College students yawn more when they are in lecture, compared to when they are in lab.
D) College students yawn more when they are exposed to higher levels of carbon dioxide.