O conveys land "to A for life, and then to the children of B." In order for the conveyance to have an indefeasibly vested remainder in fee simple absolute in the children of B, assuming that A is alive, what fact or set of facts must be true at the time of conveyance?

A) Only that one or more child of B exists at the time of the conveyance.

B) Both that B has one or more child AND that B is dead at the time of conveyance.

C) Only that B is alive and capable of having children at the time of conveyance.

D) Both that B has one or more children AND that B is alive and capable of having children at the time of conveyance.