The answer is D! Hope that helped
Answer:
Greenhouse affect - atmosphere traps heat
Ice age - coldest phase of climate cycle
Sun's output - can vary
Greenhouse gases - atmosphere traps even more heat
They have a long history of war
<span>A greenhouse gas is a gas that contributes to the greenhouse effect by absorbing infrared radiation. It is important because it keeps the Earth's surface heated and able to maintain life upon it.</span>
