Final answer:
A haplontic plant population maintains genetic diversity through fertilization and spore formation within their life cycle, featuring an alternation of generations. The correct answer is option c) and d).
Step-by-step explanation:
A haplontic plant population maintains genetic diversity primarily through sexual reproduction, specifically through fertilization and spore formation. Alternation of generations is a key process in plant life cycles, where plants alternate between haploid (gametophyte) and diploid (sporophyte) stages.
Meiosis is crucial in creating haploid spores from the diploid sporophyte, which ensures genetic variation through processes such as independent assortment and crossing over. These spores develop into haploid gametophytes by mitosis. The gametophytes then produce gametes, again by mitosis, because they are already haploid.
Fertilization occurs when these gametes meet, resulting in a diploid zygote, which ultimately grows into a new sporophyte. This constant cycling between stages introduces new gene combinations and maintains the genetic diversity in the plant population.