题目内容：
Most people think of a camel as an obedient beast of burden, because it is best known for its ability to carry heavy loads across vast stretches of desert without requiring water. In reality, the camel is considerably more than just the Arabian equivalent of the mule. It also possesses a great amount of intelligence and sensitivity.The Arabs assert that camels are so acutely aware of injustice and ill treatment that a camel owner who punishes one of the beasts too harshly finds it difficult to escape the camel’s vengeance. Apparently, the animal will remember an injury and wait for an opportunity to get revenge.
In order to protect themselves from the vengeful beasts, Arabian camel drivers have learned to trick their camels into believing they have achieved revenge. When an Arab realizes that he has exited a camel’s rage, he places his own garments on the ground in the animal’s path. He arranges the clothing so that it appears to cover a man’s body. When the camel recognizes its master’s clothing on the ground, it seizes the pile with its teeth, shakes the garments violently and tramples on them in a rage. Eventually, after its anger has died away, the camel departs, assuming its revenge is complete. Only then does the owner of the garments come out of hiding, safe for the time being, thanks to this clever ruse.
1. Which of the following is mentioned in this passage?
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