The angiospermic endosperm, except in special cases, is a triploid (3n) tissue as it is a product of triple fusion involving double fertilization. It is, thus, distinct from the endosperm of gymnosperms and heterosporous pteridophytes where the endosperm is a ...........

The correct option is B Simple haploid (n) tissue of the gametophyte not involving any complication like polar fusion or fertilization.
In gymnosperms, the endosperm is haploid in nature. Whereas, in angiosperms there is a characteristic double fertilization, where a triploid endosperm as well as a diploid zygote is formed. In angiosperms, a diploid polar secondary nuclei fuses with male gamete forming triploid endosperm, serves the role of providing nourishment to the developing embryo.