Answer:
b
Explanation:
Greenhouse gases keep our planet livable by holding onto some of Earth's heat energy so that it doesn't all escape into space. This heat trapping is known as the greenhouse effect. Just as too little greenhouse gas makes Earth too cold, too much greenhouse gas makes Earth too warm.
Answer: B.
Without greenhouse gases, Earth would be too cold for life to exist.
Explanation: How else could a greenhouse exist? It would have to be moderate temperatures.