Which structure mediates the attachment of spores to a surface on which to grow?

holdfast

Explanation:

the calvin cycle has three stages. in stage 1, the enzyme rubisco incorporates carbon dioxide into an organic molecule. in stage 2, the organic molecule is reduced. in stage 3, rubp, the molecule that starts the cycle, is regenerated so that the cycle can continue

if your own plato the answer is b. the fern transitioned from sporophyte generation to gametophyte generation.