Assertion - Natural gas is the cleanest fossil fuel.
Reason - Natural gas emits the least amount of CO₂ gas.

The correct answer is: Both A and R are true, and R is the correct explanation for A.

• Natural gas is a fossil fuel, but it's cleaner and more effective than other conventional fuels, and it emits fewer greenhouse gases and pollution than its rivals.
• Burning natural gas, for instance, results in the production of 45 percent less carbon dioxide than burning coal, 30 percent less than burning oil, and 15 percent less than burning wood. It produces heat, water vapor, and carbon dioxide upon combustion.
• Natural gas is inexpensive and widely available, with 67% of Canada's natural gas coming from Alberta, according to the energy ministry of the province.
• Natural gas is the cleanest fossil fuel, although it isn't as clean as wind or solar electricity. Many people believe that natural gas will play a significant role in the transition to a greener future.