Due to human activities, the concentration of carbon dioxide in the atmosphere has increased, but much of it does not remain in the lower part of the atmosphere, because 1. It escapes to the outer stratosphere. 2. Phytoplankton do photosynthesis in the oceans. 3. Polar ice caps capture the air. Which of the above statement(s) is/are correct?

• A. 1 and 2
• B. only 2
• C. 2 and 3
• D. only 3