Which of these would be MOST impacted by acid rain falling in the Great Lakes region of Canada and the United States?

A)
the timber industry would cease to exist

B)
water pollution would damage the fishing industry

C)
pollution would cause the lakes to freeze in winter

D)
acid raid would slow transportation on the Great Lakes

Martha participates in a research study in order to receive extra credit for her psychology class. when she arrives in the research office she is given a can of what looks and tastes like beer, but which actually contains no alcohol. in the adjoining room martha's classmate karen is also participating in the study. karen receives a can of alcoholic beer. if the experiment was designed to test the effects of alcohol on concentration, then who is exposed to the independent variable?