Answer
The correct answer would be "Diploid sporophytic generation alternating with haploid gametophytic generation"
Alternation of generation refers to the type of life cycle often observed in lower plants. In this life cycle, plants alternate between diploid and haploid stage.
For example, a diploid sporophyte produces haploid spores through meiosis
The spores mature into haploid gametophyte which produces haploid gametes through mitosis.
The gametes fertilize and restore the ploidy by producing a diploid zygote which matures into a diploid sporophyte.
