Final answer:
The dominant phase in the life cycle of ferns is the sporophyte generation, which is more prominent and larger than the gametophyte generation. Thus, the option b is the correct answer.
Step-by-step explanation:
In the life cycle of ferns, the dominant phase is the sporophyte generation. This phase is characterized by the leafy fronds of the fern that we commonly recognize. These fronds have clusters of sporangia on the undersides, which produce spores that develop into tiny, heart-shaped gametophytes. While both the gametophyte and sporophyte are free-living and multicellular, the sporophyte is much larger and more prominent in the life cycle of ferns.
The gametophyte generation, though it is an important stage in the alternation of generations, is smaller and less conspicuous than the sporophyte. It produces reproductive cells called antheridia and archegonia, which upon fertilization, give rise to the zygote that becomes a new sporophyte plant, thus continuing the cycle.