Where Did Andrew Carnegie Learn Many of the Successful Management

Where did Andrew Carnegie learn many of the successful management methods he used in the steel?

A) as a bookkeeper in the textile industry in his native Scotland.
B) as a secretary for the Singer Sewing Machine Company.
C) as a foreman in the meatpacking industry in Chicago.
D) as a bartender at an Edinburgh pub.
E) as an employee of the Pennsylvania Railroad.