ACNG
BCoal gas
CWater gas
DProducer gas
Answer:
A. CNG
Read Explanation:
CNG (Compressed Natural Gas) is an example of a natural fuel.
Why CNG is a Natural Fuel
Origin: CNG is simply natural gas (primarily methane) extracted from deep underground reservoirs. It is compressed under high pressure to be used as a clean alternative for vehicles. Because it is a fossil fuel formed by nature over millions of years, it is classified as a primary or natural fuel.
Why the Other Options are Incorrect
The other choices are all artificial or secondary gaseous fuels manufactured by human-made chemical processes:
Coal gas: Produced by heating coal in the absence of air
Water gas: A synthetic mixture of carbon monoxide and hydrogen made by passing steam over red-hot coke.
Producer gas: A manufactured mixture of carbon monoxide and nitrogen made by passing air and steam over burning coke.