Statement A: An ovule usually has a single embryo sac.

Statement B: In each ovule only one megaspore is usually formed due to reduction division in megaspore mother cell.

Each ovule usually has single embryo sac formed from a functional megaspore. In each ovule usually only one megaspore mother is differentiated from its nucellus. It undergoes reduction division and forms four haploid megaspores. Out of these, three perish and only one is functional. The functional megaspore forms the embryo sac within the nucellus of ovule.