The Most Likely Explanation for Lower Sperm Counts in Rural

The most likely explanation for lower sperm counts in rural compared to urban areas of the United States is

A) increased exposure to endocrine disruptors and other environmental pollutants in rural areas.
B) increased masturbation in urban areas.
C) increased popularity of hot tubs in rural areas.
D) increased popularity of tight-fitting jeans and horseback riding in rural areas (the "cowboy phenomenon") .
E) the combination of increased caffeine consumption and laptop use in urban areas (the "Starbucks phenomenon") .