题目选项分析

The gyrfalcon, an Arctic bird of prey, has survived a close brush with extinction, their numbers now fivefold what they were when the use of DDT was sharply restricted in the early 1970's.

The gyrfalcon, an Arctic bird of prey, has survived a close brush with extinction; its numbers are now five times greater than when the use of DDT was sharply restricted in the early 1970's.