He was punished for shirking his official work.

Answer: Option C

Slowing : reduce one's speed or the speed of a vehicle or process.
Postponing : cause or arrange for (something) to take place at a time later than that first scheduled.
Avoiding : keep away from or stop oneself from doing (something).
Delegating : entrust (a task or responsibility) to another person, typically one who is less senior than oneself.
Shirking : avoid or neglect (a duty or responsibility).

Synonym of Shirking is Avoiding