Which of the following organisms is most likely to produce greenhouse gases such as nitrous oxide and methane?

Bacteria are major producers of greenhouse gases. Denitrifying bacteria produce nitrous oxide (N2O) as a byproduct, while methanogenic archaea (often grouped with bacteria in general contexts) produce methane (CH4) in anaerobic environments like wetlands and rice paddies. Earthworms improve soil but don't directly produce these gases.