Final answer:
B holds a life estate pur autre vie which allows them to use the property for the duration of C's life, while D holds a remainder interest and will obtain full ownership of the property upon C's death.
Step-by-step explanation:
In the scenario where A gives a life estate to B for so long as C lives, and upon C's death, the property will pass to D, the interests of B and D are categorized as follows:
B holds a life estate pur autre vie, which is a type of life estate that lasts for the duration of another person's life—in this case, person C's life. This means that B has the right to possess and use the property for as long as C is alive. However, B does not have the right to pass on ownership of the property after their death or C's death, whichever occurs first.
D, on the other hand, holds a remainder interest in the property. This means that once C passes away, the life estate terminates, and D will gain full ownership and control of the property. D's interest is contingent upon the termination of the life estate, which depends solely on the longevity of C's life.