Identify the method of forming a causal hypothesis in the following example: Smoking is related to incidence of specific diseases. Medical data show that smokers are more likely to get emphysema, lung cancer, throat cancer, and heart disease, and get them younger than are nonsmokers. These reports show that smoking is a likely cause for these diseases.

A. Method of difference

B. Method of agreement

C. Best diagnosis method

D. None of the above