The sentence that is punctuated correctly is option A. On her Mediterranean cruise, Mamie visited Barcelona, Spain; Nice, France; and Pisa, Italy. A semicolon is used in this sentence because more than one of the units in the series are using the punctuation mark commas.
Explanation:
1) Coral reefs are underwater ecosystems which are formed of colonies of Coral Polyps, a Famous and well-known Coral Reef is the Great Barrier Reef, which is located off the coast of Queensland, Australia.
2) A couple of threats to the world's oceans include, Plastic Pollution, Global Warming and Acidification.
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