In the following question, out of the given four alternatives, select the one which is opposite in meaning to the given word.
Obscene

Obscene means offensive or disgusting by accepted standards of morality and decency (lewd or indecent).
Let's check the options:

Decent: Conforming with generally accepted standards of respectable or moral behavior (Exact opposite/Antonym).

Indecent / Immoral / Offensive: These are all synonyms of obscene.

Thus, 'Decent' is the correct antonym.