Which plant division has seeds with a 3n endosperm due to double fertilization?

Angiosperms have seeds with an 3n endosperm due to double fertilization.

Explanation:

Double fertilization is found only in flowering plants. In angiosperms, the female gametophyte does not grow after reaching eight nucleate stage. After fertilization and triple fusion, the zygote and primary endosperm are created and further growth of embryo sac continues. Triple fusion is the fusion of two haploid polar nuclei of female gametophyte and one male nuclei. This results in a 3n nucleus. The developing embryo obtains nutrition from the endosperm. If fertilization fails no endosperm is formed.