The Case in Point on Earnings of Economics Majors Made

The Case in Point on earnings of economics majors made all of the following points EXCEPT:

A) Firms that use maquiladoras have transferred from the United States to Mexico the stages of the manufacturing process that use more machinery and less labor.
B) It isn't clear whether the higher earnings of economics majors are due to training in economics or some sort of self-selection mechanism -- students who end up earning more may be more likely to major in economics..
C) Training in economics may be highly valued in the marketplace.
D) Students who major in economics tend to earn more in business-related fields than do students who major in business.