Double fertilization is Fusion of two male gametes with one egg; Fusion of two male gametes of a pollen tube with two different eggs; Syngamy and triple fusion; Fusion of one male gamete with two polar nuclei

Double fertilisation is a process unique to Angiosperms. After the release of two male gametes by the pollen tube, in the embryo sac, one male gamete which is near the egg fuses with the egg nucleus and this called syngamy which results in the formation of a zygote. The other male gamete fuses with the secondary nucleus and this is called triple fusion which results in the formation of a triploid primary endosperm mother cell. This simultaneous occurrence of syngamy and triple fusion in the embryo sac is called double fertilisation. So, the correct answer is option C.