Carbon cycle processes and sinks – UGC NET Question

In the carbon cycle, photosynthesis is the key biological process that takes up carbon dioxide from the atmosphere. Green plants, algae and some bacteria use CO2 and water in the presence of sunlight to produce carbohydrates and release oxygen. The carbon is stored temporarily in plant biomass and, through food chains, in other organisms. Thus, photosynthesis acts as a major carbon sink, making Option C the correct answer.

Option A:
Option A is incorrect because combustion of fossil fuels adds carbon dioxide to the atmosphere. It is a carbon source, not a sink, and contributes to climate change.

Option B:
Option B is incorrect since deforestation removes trees that would otherwise absorb CO2. It reduces the capacity of terrestrial ecosystems to act as carbon sinks and often releases stored carbon when biomass is burned or decomposes.

Option C:
Option C is correct as it points to the primary natural mechanism for withdrawing CO2 from the atmosphere. Protecting and enhancing photosynthetic ecosystems is a key strategy for climate mitigation.

Option D:
Option D is incorrect because volcanic eruptions release gases, including CO2, to the atmosphere. They are natural sources of carbon, not processes that remove it.