The correct answer is D. Methane and carbon dioxide.
Biogas is a mixture of gases produced by the breakdown of organic matter in the absence of oxygen. The main components of biogas are methane (CH4) and carbon dioxide (CO2), with smaller amounts of other gases such as hydrogen (H2), nitrogen (N2), and oxygen (O2).
Methane is a colorless, odorless, and flammable gas that is lighter than air. It is the main component of natural gas and is also produced by the decomposition of organic matter in landfills and sewage treatment plants. Methane is a greenhouse gas that contributes to climate change.
Carbon dioxide is a colorless, odorless, and non-flammable gas that is heavier
than air. It is the main component of dry air and is also produced by the respiration of animals and the burning of fossil fuels. Carbon dioxide is a greenhouse gas that contributes to climate change.The other options are incorrect because they are not the main components of biogas. Option A, carbon dioxide and oxygen, is the composition of air. Option B, isobutane and propane, are hydrocarbons that are found in natural gas. Option C, methane and carbon monoxide, is a mixture that is used in some internal combustion engines.