Researchers Have Found a General Relationship Between Testicular Cancer and Exercise.Increased

Researchers have found a general relationship between testicular cancer and exercise.Increased exercise is associated with a decrease in incidence of testicular cancer.However,a positive relationship (increased incidence of testicular cancer) was found between testicular cancer and riding bikes or horses.Several factors might be hypothesized to bring about this result.Which of these hypotheses is properly related to a prediction that arises from it?

A) Hypothesis: Riding bikes or horses causes trauma to the testes.Prediction: Bike or horse riding will cause testes to shrink.
B) Hypothesis: The seat on bikes and the saddle on horses are made of material containing chemicals that damage testicular cells.Prediction: Chemicals found in bike seats or horse saddles damage testicular cells.
C) Hypothesis: Riding bikes or horses increases scrotal temperature,which damages testicular cells.Prediction: Bike riders are more likely to wear briefs than boxers as their underwear of choice.
D) Hypothesis: Mutations that lead to testicular cancer make men more likely to ride bikes or horses.Prediction: Men who ride bikes or horses have a higher rate of mutations than nonriders.