Final answer:
This scenario is describing a "life estate" in property law where B's right to use the property is contingent on C's lifetime.
Step-by-step explanation:
If Owner A allows B to use Owner A's property as long as C is alive, this arrangement is most likely describing a form of life estate in property law. A life estate is an interest in real property that lasts for the lifetime of a specified person, referred to as the measuring life.
In this scenario, C is the measuring life and B holds the life estate, which means B can use the property for as long as C lives. Upon C's death, the property interest would revert back to Owner A or proceed to a remainderman if one has been designated in the agreement.