Correct option is A
Option (a) is the correct synonym of the given word.
Fair (noun): An event or gathering, often with amusements and activities.
Fair (adjective): Just and unbiased; free from favoritism or discrimination.
Fair (adjective): Of light complexion; not dark.
Synonyms:
Just, equitable, impartial, unbiased (adjective).
Carnival, festival, exhibition (noun).
Antonyms:
Unfair, biased, unjust (adjective).
Unfairness, discrimination, bias (noun).
Meanings of all options-
Unbiased - Not showing favoritism or prejudice; impartial.
Hollow - Having an empty space or void inside; lacking substance.
Effective - Producing the intended or desired result; efficient.
Drowsy - Feeling sleepy or inclined to sleep; lethargic.