Angiosperm Reproduction: In angiosperms, double fertilization involves two sperm cells. One fuses with the egg to form the zygote (syngamy), and the other fuses with the two polar nuclei in the central cell to form the endosperm (triple fusion).
Option Analysis:
(1) Syngamy: Refers to the fusion of male and egg gametes to form the zygote, not the central cell. Incorrect.
(2) Apomixis: Asexual reproduction without fertilization. Incorrect.
(3) Double fertilization: The overall process involving syngamy and triple fusion, not specific to the central cell. Incorrect.
(4) Triple fusion: Specifically describes the fusion of a male gamete with the central cell’s two polar nuclei. Correct.
Conclusion: The correct answer is (4) Triple fusion, as it defines the fusion with the central cell.