Sexual Reproduction in Flowering Plants — quick quiz

In a mature embryo sac of an angiosperm (Polygonum type), the cells are arranged in a specific pattern. At the micropylar end, there are three cells forming the egg apparatus, and at the chalazal end, there are three antipodal cells. The central cell contains two polar nuclei. If a mutation causes one of the synergids to possess two nuclei instead of one, and this synergid participates in the fertilisation process along with the egg, what would be the expected ploidy of the structure formed if a male gamete mistakenly fuses with this abnormal synergid instead of the polar nuclei?