Diplohaplontic life cycle refers to a type of life cycle that involves two distinct multicellular stages: a haploid (n) gametophyte stage and a diploid (2n) sporophyte stage. In this life cycle, the gametophyte and sporophyte stages are both multicellular and independent, and they alternate in generations.

The diplohaplontic life cycle can be found in various plant groups, including pteridophytes, gymnosperms, and angiosperms. Let's explore each of these groups in detail:

a) Pteridophytes:
Pteridophytes, which include ferns, horsetails, and clubmosses, exhibit a diplohaplontic life cycle. The dominant stage in these plants is the sporophyte, which is a diploid plant that produces spores through meiosis. The spores then develop into a multicellular haploid gametophyte, which produces gametes (eggs and sperm) through mitosis. Fertilization of the gametes leads to the formation of a new sporophyte, completing the life cycle.

b) Gymnosperms:
Gymnosperms, such as conifers, cycads, and ginkgoes, also display a diplohaplontic life cycle. In gymnosperms, the sporophyte is the dominant phase and produces spores. These spores develop into the haploid gametophyte, which produces gametes. The male gametophytes produce pollen grains containing the sperm, while the female gametophytes produce eggs. The pollen grains are transferred to the female reproductive structures, where fertilization occurs, leading to the development of a new sporophyte.

c) Angiosperms:
Angiosperms, commonly known as flowering plants, have a more complex life cycle known as the alternation of generations. However, they also exhibit a diplohaplontic life cycle. The sporophyte is the dominant phase in angiosperms and produces flowers. Within the flowers, the male gametophytes (pollen grains) carry the sperm, which is transferred to the female gametophyte (embryo sac). Fertilization results in the formation of a diploid zygote, which develops into a new sporophyte.

d) All of the above:
To summarize, the diplohaplontic life cycle can be observed in all of the mentioned plant groups: pteridophytes, gymnosperms, and angiosperms. This life cycle involves the alternation between a multicellular haploid gametophyte stage and a multicellular diploid sporophyte stage. The sporophyte is the dominant phase in all these plant groups and produces spores, while the gametophyte produces gametes. The fusion of gametes leads to the formation of a new sporophyte, completing the life cycle.

A) Pteridophytes