Phagocytes are blood cells that ingest and destroy microbes by phagocytosis

when atoms of different types of elements join together, they make molecules called compounds. water consists of compound molecules made up of 2 hydrogen atoms and 1 oxygen atom. this is why it's called h2o. water will always have 2 times the number of hydrogen atoms as oxygen atoms.

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