(02.01 mc) what was a lord's motivation to keep his serfs happy?

a. after five years of service, serfs were given their own tracts of land, but if the serfs were happy, they would often remain with their lord instead.
b. serfs could leave at will and serve other lords, so each lord tried to make their serfs happy so they would remain and work the fields for that lord.
c. serfs could report poor treatment by their lords to the king which could result in fines imposed upon the lord if he was found guilty.
d. the lord's wealth and success depended on the service provided by the serfs, so it was in the lord's best interest to keep them comfortable and healthy.

Option: D.The lord's wealth and success depended on the service provided by the serfs, so it was in the lord's best interest to keep them comfortable and healthy.

Explanation:

In the Middle Ages Europe was practicing feudalism where lords maintain their land by serfdom. Serfs were the peasants, belonged to the lowest feudal class, who were forced to work in fields which belonged to their lords. Serfs toiled the land for lords wealth and success as they were the source of agriculture labor. So, the lords needed to look after the serfs to keep them comfortable and healthy so they can give their best efforts in generating wealth for lords.  

question is unclear.

i can't sorry.

post the full question so i can .