GWD 9－14

The Eurasian ruffe, a fish species inadvertently introduced into North America’s Great Lakes in recent years, feeds on the eggs of lake whitefish, a native species, thus threatening the lakes’ natural ecosystem. To help track the ruffe’s spread, government agencies have produced wallet-sized cards about the ruffe. The cards contain pictures of the ruffe and explain the danger they pose; the cards also request anglers to report any ruffe they catch.

Which of the following, if true, would provide most support for the prediction that the agencies’ action will have its intended effect?

1. The ruffe has spiny fins that make it unattractive as prey.


2. Ruffe generally feed at night, but most recreational fishing on the Great Lakes is done during daytime hours.


3. Most people who fish recreationally on the Great Lakes are interested in the preservation of the lake whitefish because it is a highly prized game fish.


4. The ruffe is one of several nonnative species in the Great Lakes whose existence threatens the survival of lake whitefish populations there.


5. The bait that most people use when fishing for whitefish on the Great Lakes is not attractive to ruffe.

答案是C，我怎么觉得这5个选项一个都不对呢？C中只提到了whitefish，但是问题是问控制ruffe的方法的有效性。怎么理解？请NN指点！

9-14          http://forum.chasedream.com/dispbbs.asp?BoardID=24&ID=75100

9-14          http://forum.chasedream.com/dispbbs.asp?BoardID=24&ID=71014

Thanks a lot!