Answer : Option C) A farmer who was not allowed to leave the land on which he worked.
Explanation : A serf was a poorest class of peasants, who were farmers and served as slaves to the Lords who owned their lands. In return for a place to live where the serfs were living, they made serfs work for the land to grow crops for themselves and the lord. Also, serfs were expected to work on the farms for the lord and pay rent to him. This was the poor condition of the serfs during feudalism.