The correct option is B 250/500
Pollen grains are the male gametophytes that develop from microspores. Each diploid microspore mother cell undergoes 1 round of meiosis to give rise to 4 haploid cells arranged in a cluster which are known as microspore tetrad. Each of these microspores form pollen grains. 4 pollen grains are formed as a result of 1 meiotic division. Since there is no degeneration, 100 male gametes are developed from 100 microspores (from 25 meiotic divisions).
Each megaspore mother cell undergoes 1 round of meiotic division to give rise to 4 megaspores. But only 1 megaspore remains functional while the other 3 degenerate. 100 eggs are developed from 100 megaspores (from 100 meiotic divisions).
Number of meiotic divisions required to produce 200/400 seeds of pea would be 250/500. 200 seeds of pea would be produced from 200 pollen grains and 200 eggs. 200 pollen grains will be formed by 50 microspore mother cells while 200 eggs will be formed by 200 megaspore mother cells. So 250/500.