He has always been an elusive customer.

A. clever

B. unreliable

C. deceitful

D. quarrelsome

Answer: Option A

Solution(By Examveda Team)

Ambiguous : open to more than one interpretation; not having one obvious meaning.
Unreliable : not able to be relied upon.
Deceitful : guilty of or involving deceit; deceiving or misleading others.
Quarrelsome : given to or characterized by quarrelling.
Elusive : difficult to find, catch, or achieve.

Synonym of Elusive is Ambiguous