The correct option is
C uneasy
In this sentence we would be choosing a word alternate to the given word, "Restive"
Restive means unable to remain still, silent, or submissive, especially because of boredom or dissatisfaction.
Uneasy means causing or feeling anxiety; troubled or uncomfortable.
The above two words are synonymous
If we look into the other options,
Relaxed means free from tension and anxiety.
friendly means kind and pleasant.
Obstinate means stubbornly refusing to change one's opinion or chosen course of action, despite attempts to persuade one to do so.
Option C is correct