What was the investigation? But from my best guess I'm assuming it's the second option. This may be incorrect.
Answer: a. Haploid spores are released to form zygotes, which grow into gametophytes.
A fern has two different stages of the life cycle; the sporophyte and gametophyte. In the sporophyte, spores are released. After this life cycle comes the gametophyte or the sexual phase, <span>haploid spores are released to form zygotes, which grow into gametophytes. </span>
I think that it is atmosphere but not 100% sure you might want to double check
