Human activities in the recent past have caused the increased concentration of carbon dioxide in the atmosphere,but a lot of it does not remain in the lower atmosphere because of 1. its escape into the outer stratosphere.2. the photosynthesis by phyto-plankton in the oceans.3. the trapping of air in the polar ice caps.Which of the statements given above is/are correct ?

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