What interest in an estate passes to another party at the death of the person upon whom the life estate is based?

The correct choice is the remainder interest. A remainder interest represents the ownership interest that passes to another party after the expiration of a life estate. In a life estate arrangement, one individual has the right to use and benefit from property during their lifetime, after which the property interest automatically transfers to a designated party, known as the remainderman. This legal framework ensures that the remainder interest is tied to the death of the life tenant, marking a transition of ownership to the next party in line as established in the estate planning or legal documentation.

While a reversionary interest is also relevant, it differs in that it occurs when the property reverts back to the original owner or their heirs after the life estate ends. The life estate itself is merely the interest the individual has during their lifetime, and pur autre vie refers to a life estate that is measured by someone other than the life tenant. Thus, in this context, the remainder interest is the most accurate description of what passes to another party upon the death of the individual holding the life estate.