Under the biological species concept, a species is a group of organisms that

According to the most widely used species definition, the biological species concept, a species is a group of organisms that can potentially interbreed, or mate, with one another to produce viable, fertile offspring. In this definition, members of the same species must have the potential to interbreed.

1 and 6 for apex

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