A. the kelvin temperature scale
In my opinion, <u>natural gas</u> is a source that will be most common in the future. Considering that natural gas is a fossil fuel that is used as a source of energy for heating, cooking, and electricity generation. It is also used in stoves, ovens, clothes dryers, lighting fixtures and other appliances that are used and needed in everyday life. Imagine a life without natural gas. We wouldn't be able to heat our homes, cook our food, etc.
