The article states: Lichen are like tiny sponges. They take in food from the environment. They take in
water, too. They also, however, take in poisonous pollutants. In other locations, all
but the toughest species of lichen have been wiped out.
The author uses these sentences mostly to help the reader
A
Compare lichen to other animal species that can be found in Yosemite
B
Know that scientists believe that lichen in Yosemite will die out very soon
с
Understand how lichen take in food and water from the environment
D
Know why lichen are thought to be one of nature's best signs of air pollution