Define a greenhouse gas.

A. Greenhouse gases allow visible light to pass through and warm the Earth's surface, and prevent heat energy from radiating back out into space.

B. Greenhouse gases allow visible light to pass through and cool the Earth's surface, and prevent heat energy from radiating back out into space.

C. Greenhouse gases allow visible light to pass through and warm the Earth's surface, and also allow heat energy to radiate back out into space.

D. Greenhouse gases prevent visible light from passing through and cooling the Earth's surface, and prevent heat energy from radiating back out into space.

E. Greenhouse gases prevent visible light from passing through and warming the Earth's surface, and prevent heat energy from radiating back out into space.

The correct answer is A. Greenhouse gases allow visible light to pass through and warm the Earth's surface, and prevent heat energy from radiating back out into space.

Explanation:

The greenhouse effect of the gases is due to the fact that they transmit sunlight at a higher frequency than infrared, which heats up soil, trees and water. That heat cannot then radiate into space again like infrared radiation because the greenhouse gases partially absorb it. The effect is that the Earth's temperature rises until a completely new equilibrium temperature is reached. The most significant greenhouse gases are water vapor, carbon dioxide, methane, and tropospheric ozone.

The concentration of greenhouse gases in the atmosphere is constantly increasing at an accelerating rate due to human activities. The annual growth rate is currently two millionths of a year.