Solution -
Unicellular haploid form - A haploid spore (brown) germinates to form a haploid multicellular filament, which eventually produces haploid multicellular leafy structures (gametophytes). Gametophytes produce haploid sperm or eggs, which fuse to form a unicellular diploid zygote, which divides by mitosis to form a multicellular diploid sporophyte.
Multicellular diploid form - A life cycle in which there is both a multicellular diploid form, the sporophyte, and a multicellular haploid form, the gametophyte; characteristic of plants and some algae. Gametophyte. In organisms that have alternation of generations, themulticellular haploid form that produces haploid gametes by mitosis.