The correct option is B mitosis
The sex organs of bryophytes produce gametes by mitosis. The gametophyte or the gamete bearing part of bryophytes is haploid. Hence gamete mother cells produce gametes by mitosis.
Meiosis occurs mostly in diploid organisms to produce gametes.
Amitosis is a simple and direct method of cell division in which there is cleavage of the nucleus and division of cells without the formation of spindle fibres. It is observed in bacteria.
Multiple fission is a type of cell division where the organism divides itself into numerous daughter cells. The nucleus of the parent cell divides several times, producing several nuclei.