Methane is emitted from which of the following?

1. A

   Paddy fields only

   Flooded paddy fields emit methane from anaerobic decomposition of organic matter. That source is real, but the question also lists termite mounds. Paddy only is incomplete. This option is not the key.

2. B

   Termitary only

   Termite guts harbour methanogenic microbes, so termitaria emit methane. Termites only misses the paddy source. This option is therefore wrong as a complete answer.

3. C

   Both (a) and (b)

   Both waterlogged rice soils and termite colonies are recognised biogenic methane sources. The paper therefore keys both (a) and (b). This option is the official key.

4. D

   None of the above

   Because both listed sources do emit methane, none of the above is false. This option is not the key.

Summary. Official key is (c) Both (a) and (b). Methane is a greenhouse gas from anaerobic microbes. Flooded rice paddies and termite guts are textbook biogenic sources. Choosing only one of them leaves the other out. Only (c) covers both as asked.