啊,貌似没有人纠结于B啊 B. The decline in the number of crabs on Delaware’s beaches is due to the harvesting of crabs by humans. 为毛大家都说无关呢? 我当时徘徊在BE之间,最后觉得E无关,选了B。
题目结论是This decline, however, poses no serious threat to the migrating shorebird populations: by remaining longer in Delaware, the birds will be able to eat enough crab eggs to allow them to complete their migration.
那我们应该削弱的不是 by remaining longer in Delaware, the birds will be able to eat enough crab eggs to allow them to complete their migration. 这个原因吗?跟它迁徙后的繁殖没什么关系。
相反,看B项,蛋的减少是due to the harvesting of crabs by humans.这么说,即使鸟在那里待得再久也没用了,因为蛋都被人收走了。