Which of the following statements best describes "carbon fertilization" ?
Explanation
Carbon fertilization refers to the phenomenon where increased atmospheric $CO_2$ enhances the rate of photosynthesis, leading to accelerated plant growth and biomass production. This core concept tests the biological response of vegetation to rising greenhouse gas levels, distinguishing it from purely climatic effects. While option (b) is a common consequence of rising $CO_2$, it describes global warming rather than the specific "fertilization" effect, which acts as a nutrient-like stimulus to plant productivity.