Which of the following is NOT a method by which natural gas is created?

Combustion is a process that involves the burning of natural gas or other fuels to release energy, primarily in the form of heat. It does not contribute to the creation of natural gas itself. Instead, combustion is a means of utilizing the energy stored in fuels, such as natural gas, for heating or power generation.

In the context of natural gas formation, this is distinct from other processes listed. Drilling is a method used to extract natural gas from underground reservoirs, while biogas refers to gas generated through the breakdown of organic matter by microorganisms under anaerobic conditions. Similarly, the decomposition of organic matter is a natural process that can lead to the formation of natural gas over geological time periods. Therefore, while biogas and organic matter decomposition are directly related to the creation of natural gas, combustion serves a different purpose: it is a method of energy release rather than gas creation.