The correct option is C The male and female gametophytes remain within the sporangia retained on sporophytes
Unlike bryophytes and pteridophytes, in gymnosperms the male and the female gametophytes do not have an independent free-living existence. They remain within the sporangia retained on the sporophytes. Pteridophytes have free living, photosynthetic thalloid gametophyte called prothallus. In bryophytes, the main plant body of the bryophyte is haploid. It produces gametes, hence is called a gametophyte. Zygotes in bryophytes produce a multicellular sporophyte, that is not free-living but attached to the photosynthetic gametophyte and derives nourishment from it.