Concept:The word "hostile" means unfriendly or antagonistic. An antonym is a word with the opposite meaning.
Explanation:Hostile describes showing opposition, dislike, or aggressive intent.
The opposite of being unfriendly is being warm and kind.
"Friendly" means showing kindness and goodwill, which is the direct opposite of hostile.
For example: A hostile person is aggressive, while a friendly person is welcoming.
Other options like aggressive, rude, and bitter are similar in meaning to hostile, not opposite.
Thus, the correct antonym is "friendly".
Answer:A. Friendly