Answer:
A. an embryo sac
Step-by-step explanation:
Angiosperms or flowering plants produce their gametes through the meiosis.
In the ovule (contains female reproductive cells) a diploid cell (megaspore )undergoes meiosisin which four cells (megaspores) with haploid nuclei are produced. One of these four megaspores then undergoes three successive mitotic divisions to produce an immature embryo sac which is the megagametophyte with 8 haploid nuclei (3 antipodal cells, 2 synergid cells, 1 egg cell and 2 polar nuclei).