Task: Question Answering
Input (English): Background Paragraph: The Gaia hypothesis states that the biosphere is its own living organism. The hypothesis suggests that the Earth is self-regulating and tends to achieve a stable state, known as homeostasis . For example the composition of our atmosphere stays fairly consistent, providing the ideal conditions for life. When carbon dioxide levels increase in the atmosphere, plants grow more quickly. As their growth continues, they remove more carbon dioxide from the atmosphere. In this way, the amount of carbon dioxide stays fairly constant without human intervention. 
Story: Two boys read about the Earth, Evolutionism and the Gaia hypothesis. Brad liked Evolutionism more, while Stan preferred the Gaia theory, and agreed with it. 
Question: Which boy agreed that the amount of carbon dioxide stays fairly constant without human intervention?
Output (English): Stan.