How did the economic system of manorialism most affect nobles?
they supported peasant efforts to become self-sufficient.
they let peasants grind grain for a fee at the manor's mill.
they provided protection and gave peasants land to farm.
they rewarded peasants with money after good harvests.

The economic system of manorialism most affect nobles because they provided protection and peasants land to farm.  

Option C

Explanation:

In the economic system of manorialism Peasants worked the manor (a lord's estate). In this they would receive land, justice, and protection from the lords. Most peasants that worked on the manor were serfs (they were not free). The idea behind manorialism is that peasants and lords were connected by mutual obligations. Peasants had to ask for the lord's permission for almost everything even for marriage and Lords, in turn, had the responsibility of fixing roads and fences and providing protection during war or a raid.