Select the word from the list that best fits the definition a(n) is a substance that cannot be broken down into other substances.

A, as , to a , as a , is as a. b. c. d.

What is the result of the greenhouse effect? a. heat is deflected from the atmosphere. b. heat is released from the atmosphere. c. heat is kept in the atmosphere. d. plants are able to grow in the tropics where the air is the heaviest.

Explain: plate tectonics and people.