Top-shaped multiciliate male gametes and the mature seed which bears only one embryo with two cotyledons, are characteristic features of
polypetalous angiosperms
gamopetalous angiosperms
conifers
cycads
D.
cycads
Cycads is a group of gymnosperms, which have top shaped multiciliated male gametes (largest male gamete) and each mature seed of these plants contain one embryo and two cotyledons (dicotyledonous) eg, Cycas.