Fast - Brainiest - multiple choice - 45PTS Both Mexico City and New York City or highly populated areas why is the air pollution in Mexico much worse?

A. Mexico City receives a large amount of yearly precipitation.
B. Mexico City is surrounded by mountains that trap the polluted air.
C. Mexico City operates a larger public transit system than New York City
D. Mexico City has more factories that use cleaner fuels than New York City.

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?