What is the ratio of people living in urban areas with unhealthy air? 

A)  one in every two people 
B)  one in every six people 
C)  one in every nine people 
D)  one in every twenty people

Unhealthy Air

Air that is contaminated with pollutants at levels which are harmful to human health and the environment.

Urban Areas

Regions characterized by high human population density and vast human-built features in comparison to the areas surrounding them.

Ratio

A quantitative relationship between two numbers showing the number of times one value contains or is contained within the other.