The traditional methods of doing things have now become obsolescent.

A. harmful

B. obsolete

C. unrewarding

D. unpopular

Answer: Option B

Solution(By Examveda Team)

Harmful : causing or likely to cause harm.
Obsolete : no longer produced or used; out of date.
Unrewarding : not rewarding or satisfying.
Unpopular : not liked or popular.
Obsolescent : becoming obsolete.

Synonym of Obsolescent is Obsolete