Functional megaspore in an angiosperm develops into: Embryo, Ovule, Endosperm, Embryo sac

In angiosperms or flowering plants, the megaspore mother cell produces a functional megaspore that develops into an embryo sac through two distinct processes megasporogenesis (formation of the megaspore in the nucellus, or megasporangium), and megasporogenesis (development of the megaspore into the embryo sac, or megagametophyte).Thus, option D is the correct answer.