The Pandavas led an austere life in the mountains.

Answer: Option C

Harsh : unpleasantly rough or jarring to the senses.
Religious : relating to or believing in a religion.
Strict : demanding that rules concerning behaviour are obeyed and observed.
Unsteady : liable to fall or shake; not steady in position.
Austere : severe or strict in manner or attitude.

Synonym of Austere is Strict