Final answer:
The correct answer is that none of the given statements (A, B, or C) are entirely true regarding serfs. Serfs were not treated like slaves, and when unable to work, they were not always abandoned by their families or the church.
Step-by-step explanation:
The statement that is entirely true regarding serfs is: D) None of the above.
Serfs were indeed tied to the land under the feudal system, but they differ from slaves in that they were not considered property and could not be bought or sold. Serfdom provided serfs with protection and the right to work on and reap the benefits from a piece of land, which is contrary to the nature of slavery, where individuals have no rights or land of their own. When serfs were unable to work, it was often their families, the lord, or the church that provided for them, which shows that they were not completely abandoned as the implications of the statement C suggests.
The system that regulated the lives of serfs was based on mutual obligations. They owed their lord labor and a portion of their produce in return for protection and the right to work the land. The manorial system, a component of broader feudalism, functioned on the basis of these reciprocal relationships between lord and serf, which also ensured that serfs had certain securities unavailable to slaves.