GRE Reading Comprehension: JiJing 352-GRE阅读机经352篇 - 0VC_OFV4YULKFIOMJ

The author of the passage mentions the "unique properties" of tree species primarily in order to help explain A. why pests tend to target specific tree species B. why pests can have long-term effects on entire ecosystems C. how pests contribute to shifts in forest species composition D. how pests are able to become established in an ecosystem E. how some tree species are able to withstand the effects of pests