Like all plants, the bryophytes show alternation-of-generation. Having evolved early in the history of plants, they have sperm that swim to the ovaries. Which generation is the largest, dominant generation in the bryophytes?

The gametophyte generation is longest and largest phase

Explanation:

Bryophytes evolved from the algae group of the plants which were aquatic environment. The Chara algae which grow in the tidal region evolved to form the first plants which could grow in both water and land called bryophytes.

The bryophytes although obtained nutrition from the terrestrial environment but their gametophytic stage was dependent on the water for the fertilization.

The gametophyte which produces the gametes were larger and independent as compared to the sporophyte which was small. The gametophytes formed the dominant phase of the life cycle of the bryophytes.

Thus, The gametophyte generation is longest and largest phase is correct.