Explanation
- A
1 and 2 only
1 and 2 only. Water retention is also true.
- B
2 only
2 only. Under-counts.
- C
1 and 3 only
1 and 3 only. N-fixers also hold.
- D
1, 2 and 3
All three. Vertical-farm medium, habitat for nitrogen-fixers, and longer water hold.
Summary. Official key is (d) 1, 2 and 3. Biochar in a growing medium suits vertical farming, favours nitrogen-fixing microbes, and holds water.
Same topic · past papers
UPSC has asked this before
These previous-year questions sit on the same topic. Open one to practise the earlier ask.