Landfill gas is a mixture of many gases. It is produced by action of micro-organisms in a landfill.
Three actions occur in a landfill:
1. In the first step, volatile organic compounds are evaporated.
2. In the second step, various chemical reactions occur.
3. In the third process, is an anaerobic process which results in release of gas. The gas contains methane+ CO2 + traces of other compounds, and is known as “biogas”. This third step is also known as “methanogenesis”.
So, ‘c’ is the correct answer in the given options.