Answer:
Alternation of generations.
Step-by-step explanation:
It refers to the reproduction of some plants whose life cycle alternate between diploid (sporophyte) and haploid (gametophyte) stages.
The sporophyte represents the diploid stage which produces haploid spores through the process of meiosis.
The spores then pass through gametophyte producing male and female gametes (mitotic division).
The union of two gametes produces a diploid zygote that matures into a diploid sporophyte.