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CSAT 2023 paper

UPSC CSE CSAT 2023 · Question 42 · Reading comprehension

Which one of the following statements best reflects the most logical, rational and crucial message…

Passage—2

A global analysis of nitrogen use efficiency — a measure of the amount of nitrogen a plant takes in to grow versus what is left behind as pollution — says that using too much fertilizers will lead to increased pollution of waterways and the air. Currently, the global average for nitrogen use efficiency is approximately 0.4, meaning 40 per cent of the total nitrogen added to cropland goes into the harvested crop while 60 per cent is lost to the environment, says a study. More than half of the world's population is nourished by food grown with fertilizers containing synthetic nitrogen, which is needed to produce high crop yields. Plants take the nitrogen they need to grow, and the excess is left in the ground, water and air. This results in significant emissions of nitrous oxide, a potent greenhouse and ozone depleting gas, and other forms of nitrogen pollution, including eutrophication of lakes and rivers and contamination of river water.

CSAT 2023 · Q42

Reading comprehension Easy

Which one of the following statements best reflects the most logical, rational and crucial message implied by the passage?

Answer & explanation

Answer: (a) An enhanced efficiency of use of nitrogen is imperative for both food production and environment.

Synthetic nitrogen feeds more than half the world, yet 60 per cent of the nitrogen applied is lost as pollution. The balanced message is to use nitrogen more efficiently, keeping yields up while cutting pollution.

  • ✓ (a) The passage is built around 'nitrogen use efficiency': synthetic nitrogen is 'needed to produce high crop yields', but low efficiency (0·4) pollutes air and water. Higher efficiency serves both food and environment.
  • ✗ (b) Stopping fertilizer production is never discussed; the option defends a point the passage does not raise.
  • ✗ (c) Replacing crops is not suggested; the problem is excess application, not the crops themselves.
  • ✗ (d) Replacing conventional agriculture is too drastic when the passage says synthetic nitrogen nourishes over half the world.

Remember · When a passage shows both a need and a harm, the crucial message usually balances them rather than dropping either.

Question and answer: UPSC's official GS Paper II (2023, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). ·

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