Concept:The missing word must be an opposite of "nervous" and must fit the idea of becoming calm after initial stage fright.
Explanation:"Nervous" means easily agitated, worried, or alarmed.
When someone first takes the stage, they may feel anxious and unable to control their emotions.
The sentence shows a contrast: the initial feeling is "nervous", but the later state is different.
"Composed" means having one's feelings and expression under control; calm.
It is the direct opposite of "nervous" and correctly fills the gap.
"Balanced" and "normal" do not specifically describe emotional calmness.
"Peaceful" may seem close, but "composed" is the most precise opposite in this context of being on stage.
Answer:D. composed