What is one possible explanation for the following correlation between the two facts in the following scenario? West Virginia leads the nation in underground coal production. West Virginia also has a higher number (42 percent) of children born with birth defects in counties where coal mining is prevalent.

Coal mining causes birth defects

Explanation:

There is a correlation between West Virginia leading the nation in coal production and higher birth defects in areas where coal is mined because coal is a common denominator and might be the reason or cause these children are having birth defects.

Indeed a study conducted by researchers at Washington State University and West Virginia University on areas with mountaintop coal mining showed a high degree of birth defects as well.