Which statement explains why greenhouse gases are needed for the survival of life on Earth?
A.
Greenhouse gases are clean sources of energy.
B.
Without greenhouse gases, Earth would be too cold for life to exist.
C.
Inhaling greenhouse gases is essential for proper lung function.
D.
Greenhouse gases prevent celestial objects from entering Earth’s atmosphere.

B.  Without greenhouse gases, Earth would be too cold for life to exist.

Explanation:

Greenhouse gas (carbon dioxide) can reflect sunlight back to earth so it keeps the energy and make the planet warmer. Too many greenhouse gases make the planet too hot and cause global warming, but if its too little then the planet will be colder.

Colder temperature can also be dangerous as it will kill many organisms that can't resist it. The ideal condition should be in between, not too hot and not too cold.

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.