Antonyms are selected to be the opposite of the given words; for example, the antonym for 'kindly' is 'stern', and for 'expand' it is 'contract'.
To answer the question about choosing antonyms for given words or phrases:
The opposite of a kindly gaze is c. stern.
To expand its wings has an opposite meaning of d. contract.
An occupied seat would have the opposite of a. vacant.
If you forget the words to the song, then you would want to d. recall them.
Cooperation among players is opposed by d. competition.
To pamper my best friend is the opposite of c. neglect.
These antonym selections aim to provide a word with the most nearly opposite meaning to the words in boldface.