In angiosperms, triple fusion produces

The correct option is D Primary endospermic nucleus
Double fertilization process is observed in angiosperms in which syngamy takes place in the beginning. After syngamy the pollen tubes releases two male gametes, one fuses with the nucleus of egg cell and the other with the central cell and forms primary endosperm nucleus (PEN). The process is called as triple fusion as endosperm is triploid in nature.

So, the correct option is 'Primary endospermic nucleus'.