What is the main source of methane emissions?

The main source of methane emissions is indeed the decomposition of vegetation and the digestion in animals. Methane is a naturally occurring gas that is produced during the anaerobic decomposition process, which occurs when organic materials break down without sufficient oxygen. This process is prevalent in wetlands, landfills, and agricultural practices, particularly in the digestive systems of ruminant animals such as cows and sheep.

During digestion, these animals produce methane as a byproduct, which is released into the atmosphere. Additionally, when plant material decomposes, especially in anaerobic conditions, methane is generated. This makes biological processes a significant contributor to methane emissions, surpassing other sources.

In contrast, while fossil fuel combustion, coal mining, and petroleum refining do release greenhouse gases, their primary emissions tend to be carbon dioxide. Fossil fuel combustion, for instance, primarily contributes CO2 to the atmosphere rather than methane. Thus, option B accurately identifies the most significant source of methane emissions.