GWD24第一篇，没人问过

Elynn_Chen

2. a way in which the introduction of a bio-control agent can affect a nontarget

species.

4. The contention that biocontrol agents can

harm nontarget species by competing

with them for resources

观点类，排除其他无关的。

B和D比较, B:用的是introduction, BA affect NS

          D:用的是Contention， BA harm NS

B的适用范围更广，也就是说， 如果D对那么B也对， 但是B对D不一定对。

根据必要性，那只能选B啦。