Câu hỏi:

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct word or phrase that best fits each of the numbered blanks.

Methane (CH4) is a hydrocarbon that is a primary component of natural gas. Methane is also a greenhouse gas (GHG), so its presence in the atmosphere (11) ________ the earth's temperature and climate system. Methane is emitted from a variety of anthropogenic (human-influenced) and natural sources. Anthropogenic emission sources include landfills, oil and natural gas systems, (12) ______ activities, coal mining, stationary and mobile combustion, wastewater treatment, and certain industrial processes.

Methane is the second most abundant anthropogenic GI--IG after carbon dioxide (C02), accounting for about 16 percent (13) ________ global emissions. Methane is more than 28 times as potent as carbon dioxide at trapping heat in the atmosphere. Over the last two centuries, methane concentrations in the atmosphere have more than doubled, largely due to human-related activities. (14) ________ methane is both a powerful greenhouse gas and short-lived compared to carbon dioxide, achieving significant reductions would have a rapid and significant effect on atmospheric warming potential.

Methane is also a greenhouse gas (GHG), so its presence in the atmosphere (11) ________ the earth's temperature and climate system.