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Which of the following adds/add carbon dioxide to the carbon cycle on the planet Earth?

1. Volcanic action
2. Respiration
3. Photosynthesis
4. Decay of organic matter

Select the correct answer using the code given below.
(a) 1 and 3 only
(b) 2 only
(c) 1, 2 and 4 only
(d) 1, 2, 3 and 4



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Volcanic action releases carbon dioxide (CO2) into the atmosphere, contributing to the carbon cycle. Respiration by living organisms, including humans and animals, also produces carbon dioxide as a byproduct. Additionally, the decay of organic matter, such as dead plants and animals, releases carbon dioxide into the environment.

Photosynthesis, on the other hand, is the process by which green plants use sunlight to convert carbon dioxide and water into glucose and oxygen. It does not add carbon dioxide to the carbon cycle but instead removes it from the atmosphere.


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