How many meiotic divisions are required for formation of 100 functional megaspores?

The correct option is A 100
Diploid megaspore mother cell undergoes meiosis and gives rise to four haploid megaspores. Three of the four megaspores degenerate and only one megaspore remains functional and develops into an haploid embryo sac or the female gametophyte. So, only 25 meiotic division is required for 100 megaspores. But, for 100 functional megaspores, 100 meiotic divisions are required.