He does unpaid work for the Red Cross.

A. Honorific

B. Honest

C. Honorary

D. Honourable

Answer: Option C

Solution(By Examveda Team)

One word substitute is Honorary.

Honorific: given as a mark of respect but having few or no duties.
Honest: free of deceit; truthful and sincere.
Honorary: (of an office or its holder) unpaid.
Honourable: bringing or deserving honour.