The correct answer is a - silicon dioxide.
Diatoms are single celled algae. They have a silica - based cell wall called a frustule, which gives each diatom a particular shape.
Diatoms exist as separate single cells although some may be found in groups or colonies. The ones found in colonies create very pretty forms: leaf shaped, oval , star and even like a period.
Outer shells of diatoms are quite valuable. They are used in industry in the manufacture of toothpaste to give it grit.
Ferns are pointy and mosses is not!
The correct answer is D.) The sun
The sun’s heat causes liquids to evaporate into water vapor, which rises and forms clouds. The whole water cycle repeats itself again because of the sun.
the letter B. that is the answer
