[解析]
(1)推理判断题。根据第一段Females live in groups with their children,and quickly run out of the food supply.They hit the road in search of food.Male elephants live alone,so they don't use resources as quickly as the females.Instead,they migrate during their mating cycle.(雌性和它们的孩子一起生活,很快就会耗尽食物供应。他们出发去寻找食物。公象独自生活,所以它们消耗资源的速度不如母象快。相反,它们在交配周期内迁徙。)可知从第一段中我们可以了解到大象迁移有不同的原因。故选C。
(2)段落大意题。根据第二段During migration,elephants face short water supplies and extremely high temperatures.But people are their number﹣one problem.(在迁徙过程中,大象面临着缺水和极高的温度。但人是他们的头号问题。)可知文章第二段主要讲的是迁徙的困难。故选C。
(3)细节理解题。根据倒数第二段"To unlock the secret of where elephants move and how they move,we place collars(项圈)with a satellite unit inside,"Dr.Michael Chase says.("为了解开大象移动的位置和方式的秘密,我们在里面放置了一个带有卫星装置的项圈。"迈克尔•蔡斯说。)可知科学家要使用项圈是为了用科技追踪大象。故选B。
(4)标题归纳题。阅读全文可知这篇短文主要介绍了非洲大象的迁徙习性、面临的挑战以及保护措施。所以"C.Ready for the Move准备搬家"为最佳标题。故选C。