Use the information to answer the following question. Both Mexico City and New York City are highly populated cities.

Why are air pollution levels in Mexico City greater than they are in New York City?

A.
because Mexico City receives a large amount of yearly precipitation

B.
because Mexico city is surrounded by mountains that trap the polluted air

C.
because Mexico City operates a larger public transit system than New York City

D.
because Mexico City contains more cars and buses than New York City