题目内容：
The CompassThe great sea voyages of Europe's “Age of Discovery”, such as Christopher Columbus’s trip to the West Indies in 1492, would have been impossible without the use of a compass． This great device for sea voyage was introduced to the West from China during the thirteenth century A．D．We have to thank ancient Chinese for their invention of the compass．
Two thousand years ago the Chinese had already developed a working compass． Apiece of lodestone(天然磁石)would be cut into the shape of a ladle (长柄勺)． Placed on a stone board with a smooth surface, the loadstone would move round until the “handle” of the ladle pointed south while the bulk (主体) of the ladle was attracted to magnetic north(北磁极)． This interestingly shaped device is mentioned in a book from about A．D． 80．Other ancient books may have dated it as far back as the fourth century B． C．Jade findersplayed an important role in the invention of the "ladle"． They traveled great distances to look for jade． In order not to lose directions, they would take a "ladle" with them．
The jade connection is important． Lodestone is a hard material though not as hard as some jade(玉石)． And the making of a magnetic "ladle", as well as a highly smooth stone board, would have required great skill． This suggests that the compass was invented by the jade finders of ancient China．
However, the making of a "ladle" was a tough job． Much work needed to shape a piece of lodestone into a ladle would mean much of its natural magnetism(磁性)had been lost ． This again meant that only a few "ladles" could have been produced． Small numbersof ladles produced and growing need for navigation led to a search for ways to produce more compasses, and at the same time, smaller and better compasses．What is the first paragraph mainly about？ A．Columbus was a great sailor and discovere
B．The compass was invented by Columbu
C．The invention of the compass is important in human histor
D．Columbus introduced the compass to the West Indie
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