Use this passage to answer the next 7 questions:

The presence of gases in earth’s atmosphere is a constant. Certain gases can absorb and hold onto heat from their environment. These gases are typically comprised of three molecules held together tenuously, which causes them to vibrate when they absorb heat. The motion of their vibrations leads to the release of their stored heat to the outside environment. The heat they release is typically quickly absorbed by other similar gases nearby. These gases remain in earth’s atmosphere for a long time after being introduced. Because of this they can trap heat within the atmosphere, preventing it from leaving, by absorbing heat and releasing heat to be absorbed by other nearby similar gases.

Hypothesis 1

Gases such as methane and nitrous oxide trap heat in the earth’s atmosphere. Trapping heat in the earth’s atmosphere leads to a greenhouse effect, gradually increasing the temperature of the earth. This increase in the earth’s temperature will lead to the melting of glaciers, increasing sea level.

Hypothesis 2

Gases such as methane but not nitrous oxide trap heat in the earth’s atmosphere. The heat methane traps in the earth’s atmosphere is less than the heat that escapes the earth leading to a global cooling effect, gradually decreasing the temperature of the earth. This decrease in earth’s temperature will lead to the development of more glaciers, decreasing sea level.

Hypothesis 3

Gases such as nitrous oxide but not methane trap heat in the earth’s atmosphere. The heat nitrous oxide traps in the earth’s atmosphere is equal to the heat that escapes the earth leaving the temperature of the earth generally unchanged. The earth’s environment will remain largely unchanged by the heat trapping properties of nitrous oxide. 

1. Which hypothesis, if any, asserts that the effect on temperature of heat trapping gases is negligible?