ESSENTIAL :

A. Desirable

B. Advisable

C. Beneficial

D. Unavoidable

Answer: Option D

Solution(By Examveda Team)

Desirable :catchy, glamorous, pleasing, fetching, likable.
Advisable : to be recommended.
Beneficialresulting in good; favourable or advantageous.
Unavoidable :not able to be avoided, prevented, or ignored; inevitable.
Essential :absolutely necessary; extremely important.

Synonym of Essential is Unavoidable.