单选题：Caribbean Islands　　What would you see if you took a cruise t

　　Caribbean Islands
　　What would you see if you took a cruise to the Caribbean Islands Palm trees and coconuts （椰子） White beaches and clear, blue ocean Colorful corals （珊瑚） and even more colorful fishes and birds You bet.
　　There are thousands of islands in the Caribbean Sea. They are famous for their warm, tropical climate and great natural beauty.
　　The Caribbean Islands form a chain that separates the Caribbean Sea from the rest of the A．tlantic Ocean. （46） Many of the islands were formed by the eruption（爆发） of ancient volcanoes （火山）. Others are low-lying coral islands that gradually rose from the ocean.
　　The Caribbean Islands are known by several names. （47） The explorer Christopher Columbus called the islands the Indies in 1492 because he thought he was near the coast of India. Later, Spain and France called the islands the A ntilles.
　　There are four large islands in the Caribbean Sea. （48） These four islands are often called the Greater A ntilles. Together, they account for about 90 percent of the land area of the Caribbean Islands.
　　The rest of the Caribbean Islands are much smaller. （49） You can see why pirates such as the famous Blackbeard sailed these waters. There are countless small islands to bury treasure or hide on.
　　The weather of the Caribbean Sea is almost always warm and sunny. Sandy beaches line the coasts of many islands. （50） Many tourists arrive on cruise ships.
A．But life on the Caribbean Islands is not always paradise.
B．The earliest name used by Europeans is the Indies, later changed to the West Indies.
C．They're like a long necklace that stretches between North and South America.
D．They are Cuba,.Puerto Rico, Jamaica, and Hispaniola.
E．This is why millions of tourists visit the islands each year.
F．Some of these islands are no more than tiny slivers （小片） of exposed coral.
请选择（46）处的最佳答案．