The correct option is B triploid nucleus
Endosperm is the food laden tissue formed during the development of angiospermous seed which provides essential nutrients to the growing embryo and also the young seedling at the time polar nuclei (or secondary nucleus) to form the two polar nuclei (or secondary nucleus) to form the triploid primary endosperm nucleus. Development of endosperm from triploid primary endosperm nucleus occurs in the central cell of embryo sac.