Answer:
C, D, E
Explanation:
A: When plants photosynthesize, they actually use carbon dioxide in the process. Therefore, that would decrease the amount of carbon dioxide, so this choice is wrong.
B. Eating a sandwich has no effect on carbon dioxide levels.
C. If an animal dies, they are broken down by decomposers. During this process, any carbon in the animal's body is released into the atmosphere as carbon dioxide. This would increase the amount of carbon dioxide.
D. As stated before, plants photosynthesize. If we cut down trees, there will be fewer plants to take in carbon dioxide during photosynthesis. This will increase carbon dioxide levels.
E. When a car converts fuel into energy to move the car, carbon dioxide is released. Driving a car will increase carbon dioxide in the atmosphere.
C, D and E are correct.