Respuesta :
The revision best expands the sentence to create a more formal style over time, coral reefs have been damaged by human activities.
What are coral reefs?
Coral reefs are found underwater, stick to the stones. They are protected by a hard exoskeleton made up of calcium carbonate.
Many fishes and other animals live in the corals. They clean the water. Many human activities, such as fishing, boating, etc. damaging the corals of the water bodies.
Thus, the correct option is B. Over time, coral reefs have been damaged by human activities.
Learn more about coral reefs
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