Answer:
a. Self-monitoring.
Step-by-step explanation:
Self-monitoring is a personality attribute that an individual makes or does to monitor how he/she behaves and to monitor and regulate one's behavior. This allows the person to be conscious of the way he/she behaves or responds to social environments and situations.
In the given case of Cody refraining from speaking up about his ideas, he's exhibiting the self-monitoring personality dimension. This means that he's monitoring himself, holding himself from expressing his ideas. Rather, he patiently keeps quiet and listens to Charlotte speak.
Thus, the correct answer is option a.