Answer:
The correct answer would be d. sporophyte.
The sporophyte is a diploid stage of a plant which practice alternation of generation.
Sporophyte refers to the asexual stage of a plant as they produce haploid spores with the help of meiotic division.
The spores divide with the help of mitotic divisions and lead to the formation of the haploid gametophyte.
It produces gametes which fertilize with each other to produce a diploid plant or sporophyte.