Question ID:PT68 S3 Q7 Passage:Researcher: Accurate readings of air pollution are expensive to obtain. Lichens are complex plantlike organisms that absorb airborne pollutants and so may offer a cheaper way to monitor air quality. To investigate this, I harvested lichens at sites plagued by airborne copper pollution, determined the lichens' copper concentration, and compared the results with those acquired using mechanical monitoring devices. The lichens were as accurate as the best equipment available. Thus, lichens can effectively replace expensive pollution-monitoring devices without loss of information. Stem:Which one of the following, if true, most strengthens the researcher's argument? Correct Answer Choice:EChoice A:Mechanical monitoring devices have not already been installed in areas where air pollution is a serious problem. Choice B:Copper particles are a component of air pollution in several locales. Choice C:Experiments have shown that lichens thrive in areas where air pollution is minimal. Choice D:Lichens can easily be grown in laboratories. Choice E:Lichens absorb all other significant air pollutants in a manner similar to their absorption of copper.