What was the relationship between peasants and serfs?

AMost peasants were also serfs.
BSerfs were always below peasants in the medieval hierarchy.
CSerfs worked in the manor house, and peasants worked on the land
DSerfs had more freedom than peasants.

Verified Answer :

"c. Serfs worked in the manor house, and peasants worked on the land" would be the best option from the list. Although in general the serfs were considered to have a better condition of living, they were still not well-off relative to the nobles. 

My best guess is A. Most peasants were also serfs. I just took the test :P