Correct Option (A):
Carbon fertilization refers to the phenomenon where an increased concentration of carbon dioxide (CO₂) in the Earth's atmosphere leads to enhanced rates of photosynthesis and, consequently, increased plant growth. Plants utilize atmospheric CO₂ as a primary raw material for photosynthesis. Higher atmospheric CO₂ levels can stimulate this process, particularly in C3 plants (e.g., wheat, rice, soybeans, trees), by increasing the availability of carbon for fixation. Studies have observed a global "greening" effect, indicating an increase in leaf area and vegetation, partly attributed to elevated CO₂ levels. However, this effect is often limited by other environmental factors such as water availability, nutrient deficiencies (especially nitrogen), and temperature.
Incorrect Options:
Option 2 describes global warming, which is the long-term heating of Earth's climate system observed since the pre-industrial period due to human activities, primarily fossil fuel burning, which increases heat-trapping greenhouse gas levels in Earth's atmosphere. While increased CO₂ concentration is a major driver of global warming, it is a distinct phenomenon from carbon fertilization.
Option 3 describes ocean acidification. This process occurs when excess atmospheric CO₂ dissolves into seawater, forming carbonic acid (H₂CO₃). This leads to a decrease in the ocean's pH, making it more acidic, and can have detrimental effects on marine ecosystems, particularly on organisms that form shells or skeletons from calcium carbonate.
Option 4 is a broad and general statement about adaptation to climate change. While living beings do adapt to environmental changes, "carbon fertilization" is a specific ecological and physiological response of plants to elevated CO₂ levels, not a general adaptation of all living beings to climate change.