The correct option is C triploid cell
Triple fusion occurs in the central cell of the embryo sac.
The fusion of two haploid polar nuclei with one male gamete is called triple fusion.
This fusion of three haploid nuclei (two polar nuclei and one nucleus of male gamete) results in the formation of triploid nucleus (3n).
The triploid nucleus is called primary endosperm nucleus (PEN).
Thus, after triple fusion, the central cell becomes triploid (3n) and is called the primary endosperm cell (PEC).