Answer:
If we could see your choices, it would better help us to help you.
Explanation:
But, if you are referring to the most widely accepted theory:
Anthropogenic (man-made) Global Warming, or AGW. The theory states that man-made greenhouse gases, primarily carbon dioxide (CO2 ), are the predominant cause for the global warming that has occurred during the past 50 years.
That students who study make better grades than those who do not.
Well from the statements is pronounced it is an observation.