Answer: a. Railroad loading
Explanation:
This question relates to the BCG matrix which allows a company with multiple divisions to know how to deal with its various divisions based on their growth rate and market share.
The question specifically relates to a matrix called "Cash cows". Cash cows are divisions that have a significant market share but a low growth rate. These divisions are stable and bring more money into the company than they cost to run.
This allows us to take profits from them and invest in other. The Railroad loading controls a significant market share of 75% but has a low growth rate so is a Cash cow.