Answer:
D) the diploid sexual life cycle
Step-by-step explanation:
This life cycle occurs in most algae and its main characteristic is the alternation of generations, alternating a gamete-producing haploid phase and a spore-producing diploid phase. This life cycle is characterized by the phases: Diploid zygote -> Mitosis -> Diploid adult -> Meiosis -> Sperm and haploid eggs -> Fertilization -> Diploid zygote.
We call the diploid phase sporophyte and its duration varies according to the species considered. In bryophytes the gametophytic phase is longer lasting than the sporophytic, while in angiosperms the sporophytic phase is the most lasting.
The sporophyte (2n) has spore producing cells. Spores are haploid, so there is meiosis in their production. The spores are released into the environment and when they find a suitable location will give rise to gamete-producing haploid organisms.
These gamete producers are gametophytes, and represent the gametophytic generation. The gametes merge into a diploid organism, the zygote, which grows and develops, giving rise to the sporophytic phase.