单选题 Most disposable plastic containers are now labeled with a code number (from 1 to 9) indicating the type or quality of the plastic. Plastics with the lowest code numbers are the easiest for recycling plants to recycle and are thus the most likely to be recycled after use rather than dumped in landfills. Plastics labeled with the highest numbers are only rarely recycled. Consumers can make a significant long-term reduction in the amount of waste that goes unrecycled, therefore, by refusing to purchase those products packaged in plastic containers labeled with the highest code numbers.
Which one of the following, if true, most seriously undermines the conclusion above?

A、 The cost of collecting, sorting, and recycling discarded plastics is currently higher than the cost of manufacturing new plastics from virgin materials.
B、 Many consumers are unaware of the codes that are stamped on the plastic containers.
C、 A plastic container almost always has a higher code number after it is recycled than it had before recycling because the recycling process cause a degradation of the quality of the plastic.
D、 Products packaged in plastics with the lowest code numbers are often more expensive than those packaged in the higher-numbered plastics.
E、 (E) Communities that collect all discarded plastic containers for potential recycling later dump in landfills plastics with higher-numbered codes only when it is clear that no recycler will take them.

【正确答案】 C

【答案解析】[解析] 消费者们只购买那些装在较低编号的塑料包装内的产品，可以使塑料废物量减少，但是如果这些具有较低编号的塑料外包装，在回收再处理时，质量一直在下降，那么就不能使不可回收的废弃塑料长期显著地减少，因此(C)是正确答案。选项(A)、(B)和(D)似乎也能削弱本题的结论，但是应该注意的是本题只是在讨论消费者们可以拒绝购买那些包装在最高编号的塑料包装内的产品，也即本题是在讨论一种可能性，而非必要性，因此(A)、(B)和(D)都是错误的；(E)是无关选项。