Answer:
A
Step-by-step explanation:
Natural gas is flammable. A natural gas leak in a house can cause potential fires, and inhaling the gas can cause natural gas poisoning.
* Answer B: The fact that scientists have developed new ways of extracting natural gas - is an advantage, not a disadvantage.
* Answer C is wrong, because compared with some other fossil fuels, natural gas emits the least amount of carbon dioxide into the air when combusted -- making natural gas the cleanest burning fossil fuel of all.
* Answer D: the content of the statement is about the production process, not about using of natural gas.
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