EXPONENT :

A. Meddler

B. Cancel

C. Advocate

D. Horrid

Answer: Option C

Solution(By Examveda Team)

Meddler : one who interfere in something that is not one's concern.
Cancel :decide or announce that (a planned event) will not take place.
Horrid :causing horror.
Advocate :a person who publicly supports or recommends a particular cause or policy.
Exponent :a person who supports an idea or theory and tries to persuade people of its truth or benefits.

Synonym of Exponent is Advocate.