The structure that results when atoms are joined together by covalent bonds is called a(an) . molecule

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

some fungi obtain their nutrients from a living host (plant or animal) and are called most biotrophic fungi have fairly narrow host ranges—they are specialized on a limited called rhizomorphs that allow the fungus to grow from one tree to another. ascospores are formed inside a sac-like structure called an ascus. so your answer is a