Greenhouse Gases and Their Impact on Global Warming

Steps:

• Identify global warming cause: accumulation of greenhouse gases (GHGs) like CO2 and methane that trap heat.
• Assess option A: animal digestion produces methane, a potent GHG accelerating warming.
• Assess options B and C: fossil fuel burning and vegetation decomposition release CO2 and methane, increasing GHG levels.
• Assess option D: photosynthesis absorbs CO2, reducing atmospheric GHGs and slowing warming rate.

Why D is correct:

• Photosynthesis converts CO2 into oxygen and biomass via 6CO2 + 6H2O → C6H12O6 + 6O2, directly mitigating global warming by lowering GHG concentrations.

Why the others are wrong:

• A: Methane from animal digestion is a strong GHG, contributing 25-30% to warming.
• B: Fossil fuel combustion emits CO2, the primary driver of recent warming.
• C: Vegetation decomposition releases CO2 and methane, enhancing GHG buildup.

Final answer: D