Some student research assistants are helping study the craft brewing industry. The study primarily involves three variables. First, the size of the beer-brewing companies sometimes leads to a change in variable, the growth of these companies for the year. However, sometimes a third variable, the average price of their products (which is associated with the size of the beer-brewing companies and causes changes in the growth of these companies for the year) interferes with the result. In statistics what do we call the size of the beer-brewing companies?

A. The Fallacy

B. The Standard Deviation

C. The probable cause

D. The Outcome/Effect

E. None of the Above