Alandowner was the owner in fee simple of a tract of land. the landowner conveyed the tract to her neighbor, "for life and then to the first child of my neighbor's only sister who shall reach the age of 21." the sister was unmarried and childless at the time of the conveyance. five years later, the sister married, and she gave birth to a son the following year. when the son reached the age of 21, he brought an action in ejectment against the neighbor, who is still alive and living on the tract of land. which of these is the neighbor's best defense against the son's attempt to eject her? a the neighbor's life estate was not subject to termination during her lifetime. b the son has no claim to the tract, because he was not living at the time of the landowner's original conveyance. c a conveyance of the tract to the son violates the rule against perpetuities. d the son's interest, if any, would be that of a contingent remainder, and the contingency is the neighbor's death.