Explanation
- A
1 only
Statement 1 is false. Indian Railways bio-toilets use a bacterial (anaerobic) inoculum developed with DRDE, not a fungal inoculum. ‘1 only’ is not the key.
- B
2 only
Statement 2 is false. Anaerobic digestion yields methane, carbon dioxide and water, among other residues; ammonia and water vapour are not the only end products, nor are they simply vented as the sole outputs. This option is therefore wrong.
- C
Both 1 and 2
Both statements fail. This option is not the key.
- D
Neither 1 nor 2
Neither statement is correct: the inoculum is bacterial, and the gas/water story in statement 2 is wrong. This option is the official key.
Summary. Official key is (d) Neither 1 nor 2. Bio-toilets on Railways rely on anaerobic bacteria that digest human waste in tanks under the coach. Fungi are not the starter culture. End products include biogas (methane and CO2) and treated effluent, not ‘only ammonia and water vapour’. Both claims therefore fall.
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