Question

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a study in the 1990s found that residents of mexico city had higher levels of lead and cadmium in their blood than did residents of any other urban area in the world. what is the most likely explanation for this? a diet b heredity c air pollution d water pollution

Explanation:

Mexico City has long - standing air pollution issues. In the 1990s, industrial activities, vehicle emissions (before widespread catalytic converters and cleaner fuel standards in many parts of the world), and the city's geographical location (a basin that traps pollutants) contributed to high levels of air - borne pollutants. Lead was once a common additive in gasoline (leaded gasoline), and cadmium can be released from industrial processes and waste incineration. Diet (A) would be a more individual - level factor and not likely to cause such a widespread, city - wide difference. Heredity (B) is a genetic factor and not related to environmental pollutant levels in the blood. Water pollution (D) could be a source of some heavy metals, but air pollution (C) is a more prominent and well - known cause of high lead and cadmium levels in Mexico City's population during that era, especially considering the historical use of leaded gasoline and industrial emissions.

Answer:

C. air pollution