Question

Covering 71 percent of Earth's surface, the oceans play an essential role in maintaining the conditions for human existence on land, moderating temperature by the absorption of heat and carbon dioxide, and giving pure water back to the atmosphere through evaporation.

• A. Covering 71 percent of Earth's surface, the oceans play an essential role in maintaining the conditions for human existence on land, moderating
• B. Covering 71 percent of Earth's surface and playing an essential role in maintaining the conditions for human existence on land, the oceans moderate
• C. The oceans cover 71 percent of Earth's surface and play an essential role in maintaining conditions for human existence on land, and by moderating
• D. The oceans cover 71 percent of Earth's surface, play an essential role in maintaining the conditions for human existence on land, and moderate
• E. The oceans cover 71 percent of Earth's surface, playing an essential role in maintaining the conditions for human existence on land, and they moderate

Answer 1

The correct option is A Covering 71 percent of Earth's surface, the oceans play an essential role in maintaining the conditions for human existence on land, moderating

The meaning of the sentence is clear and logical- the oceans that cover 71% of the Earth's surface play an essential role in maintaining the conditions necessary for humans to exist on Earth. Oceans do this by maintaining and moderating the temperature by absorbing heat and carbon dioxide, and giving pure water back to the atmosphere through evaporation. All the actions mentioned in the sentence are parallel (verb-ing forms- maintaining, moderating, giving). The original sentence is perfect as it is. Thus, option A is the correct answer.