Out of the given options, choose the one which can be substituted for the given phrase\ sentence:

'Work for which no regular salary is paid'

Honorary

The correct answer is Honorary.

• Ad hoc means "for a particular purpose" or "for a specific task."
• Honorary means "conferred as an honor or distinction, without remuneration."
• Honourable means "having or showing high moral principles and standards."
• Temporary means "lasting for a limited period of time."