This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Environment and health, Subject name: Social & Preventive Medicine
Which of the following is/are the source/sources of methane, a greenhouse gas? 
Select and explain. 
A. Cattle, B. Rice fields & Wetlands, C. Cattle and rice fields, D. Cattle, rice fields and Wetlands
D: Cattle, rice fields and Wetlands
Answer: D: Cattle, rice fields and Wetlands 
Explanation: Most of Eah's methane is biogenic and is produced by methanogenesis, form of anaerobic respiration only known to be conducted by some members of the domain Archaea. Methanogens occupy landfills and other soils,ruminants (for example cows or cattle), the guts of termites, and the anoxic sediments below the seafloor and the bottom of lakes. Rice fields also generate large amounts of methane during plant growth. Ref: Internet