Perisperm is a tissue found in some seeds, derived from the nucellus, and it provides nourishment to the developing embryo. The ploidy level of perisperm is 2n, which is diploid, because it is derived from the diploid nucellus tissue of the ovule. This makes it different from the endosperm, which is usually triploid (3n) in many plants.
Thus, the correct ploidy of perisperm is 2n.