阅读下列短文，从每题所给的（A、B、C和D）四个选项中，选出最佳选项。

　　Did unicorns ever really exist?This is a question that re-mains unanswered today．Some believe that，like the dragon，the unicorn never existed and was simply an animal from afairy tale or mythology'．Others believe that the unicorn stillexists in remote regions of the earth,and can be seen only bypeople of exceptional virtue and honesty．There are still others who believethat the unicorn was a type of sacred animalthat came to earth from heaven and eventually became a human in order to survive．Someday,they believe,these humans will become unicorns once again．A final point of view isthat．like the dinosaur,unicorns once existed but became extinct．This theory suggests that because the unicom's horn（角）was used as a type of medicine,humans hunted the ani-mal out of existence．

　　Animals such as the narwhal may provide evidence（证据）,or give us a clue,that unicorns once existed on earth．The male narwhal is a huge sea creature that can be found in the Arctic seas．This animal has a single horn,or tusk,that projects from its forehead-similar to that of the unicom．In fact,in the seventeenth century,people often confused（混淆）the narwhal's tusk with the horn of the unicorn．The similarity of the male narwhal to the unicom has led some people to believe that perhaps the unicorn is the narwhal's ancestor,or vice versa（反之亦然）．Although narwhals have also been hunted for centuries,they may have escaped extinction for different reasons:they are only found in certain parts of the world,and are hunted by only a relatively small number ofpeople．

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