The correct option is (c).
Explanation
Global warming is driven by the enhanced greenhouse effect, primarily caused by the accumulation of greenhouse gases (GHGs) such as carbon dioxide (CO2) in the atmosphere. Vegetation plays a critical regulatory role in the global carbon cycle.
- Statement 1 is Correct: Photosynthesis is the biological process by which plants, algae, and some bacteria convert light energy into chemical energy. During this process, plants absorb carbon dioxide (CO2) from the atmosphere and water from the soil to produce glucose and release oxygen.
- Statement 2 is Incorrect: Forests function as major carbon sinks. When forests are cleared (deforestation), the capacity of the biosphere to absorb CO2 diminishes. Consequently, the amount of carbon dioxide in the atmosphere increases rather than decreases. Additionally, if the cleared wood is burned or left to decompose, the stored carbon is released back into the atmosphere as CO2.
- Statement 3 is Correct: Carbon dioxide is a greenhouse gas. It allows shortwave solar radiation to pass through to the Earth's surface but absorbs the longwave infrared radiation (heat) emitted back by the Earth. By trapping this heat in the lower atmosphere, CO2 contributes to the warming of the planet.
Key Takeaway: Deforestation exacerbates global warming by reducing the Earth's capacity to absorb CO2, a greenhouse gas that traps terrestrial heat radiation.