Final answer:
CNG is considered better than other fossil fuels because its combustion leaves little or no residue. The presence of carbon in CNG is reduced compared to other hydrocarbons, making it more environmentally friendly, and it is also more easily available thanks to advances in extraction technology. The correct option is A.
Step-by-step explanation:
Compressed natural gas (CNG) is proposed to be a better alternative to fossil fuels for a variety of reasons. One of the key benefits of CNG is that its combustion leaves little or no residue, which helps to reduce air pollution and the problem of waste disposal associated with some other fossil fuels. Natural gas consists primarily of methane (CH4), a molecule with one carbon atom, contrary to the proposal that CNG has an absence of carbon. In reality, the presence of carbon is reduced compared to longer-chain hydrocarbons. CNG is also considered more environmentally friendly in terms of reduced greenhouse gas emissions, producing less carbon dioxide per unit of energy compared to coal or oil. One should note that natural gas is still a fossil fuel and thus non-renewable, but technologies such as fracking have improved the ability to extract it, making natural gas more easily available and therefore a more viable energy alternative currently.
In conclusion, the correct option that makes CNG a better alternative to other fossil fuels is A. combustion leaves little or no residue. This is because natural gas, as used in CNG, burns more cleanly than other fossil fuels, producing fewer byproducts. However, it does not mean that there is an absence of carbon in CNG, so option B is incorrect. While CNG is becoming more available due to technological advancements, easiness of availability alone does not inherently make something a 'better' alternative environmentally or energy-wise, which eliminates option C as the primary reason for CNG's comparative advantage.