Answer:
b. gametophyte mitosis
Explanation:
Plants have diploid sporophyte generation. The diploid spore mother cells of the sporophyte generation undergo meiosis to produce haploid spores. These spores divide by mitosis to produce haploid gametophyte. Therefore, plants have haploid gametophytes. These haploid gametophytes form gametes by mitosis. So, gametophyte mitosis gives rise to gametes in plants.
For example, the haploid microspores are produced in anthers of flowering plants by meiosis in the microspore mother cells. These haploid microspores give rise to haploid gametophytes which in turn divide mitotically to produce haploid male gametes.
