Correct Option (A)
The passage highlights a critical global issue: low nitrogen use efficiency (NUE) in agriculture. It states that while synthetic nitrogen fertilizers are essential for high crop yields and global food security, a significant portion (approximately 60%) is not utilized by plants, leading to severe environmental pollution. This pollution manifests as nitrous oxide emissions (a potent greenhouse gas), eutrophication of waterways, and contamination of river water. Therefore, the most logical and crucial message is that enhancing nitrogen use efficiency is imperative to simultaneously ensure sustained food production and mitigate environmental degradation.
Incorrect Options:
- Option (B) is incorrect because while the passage acknowledges the current necessity of synthetic nitrogen fertilizers for food security, its central message is not about the impossibility of stopping their production or the absence of alternatives. Instead, it emphasizes the need to improve the efficiency of their application to reduce adverse impacts.
- Option (C) is incorrect because the passage does not advocate for identifying and cultivating alternative crops that require less nitrogen. Its focus is on optimizing the management and utilization of nitrogen within existing agricultural practices to minimize waste and pollution, irrespective of the crop type.
- Option (D) is incorrect because the passage does not propose a complete replacement of conventional agriculture with agroforestry, agroecosystems, or organic farming. While these are alternative agricultural systems, the passage's core message pertains to improving nitrogen management and efficiency within the context of current fertilizer use, rather than advocating for a fundamental shift in farming methods.