Question ID:PT88 S4 Q12 Passage:A lichen is made up of a photosynthetic organism and a fungus growing in symbiosis on a solid surface. Lichens absorb minerals from air and rainwater but also from the surfaces on which they grow; they cannot excrete the elements they absorb. Some varieties are very vulnerable to toxic compounds, including compounds found in polluted air. Such compounds can damage both of the symbiotic partners. Stem:Which one of the following is most strongly supported by the information above? Correct Answer Choice:EChoice A:Lichens would not be vulnerable to toxic compounds if they could excrete the elements that they absorb. Choice B:The return of lichens to a region indicates that the air quality has improved there. Choice C:The absence of lichens in a region indicates that the air is probably polluted in that area. Choice D:The photosynthetic organism and the fungus that make up a lichen can also thrive independently of each other. Choice E:Serious air pollution in a region can cause problems for lichens.