Answer:
The correct answer is the option A: Difference between the marginal cost and the price of the monopolistic competitor.
Explanation:
To begin with, the concept known as "Markup" in the field of business and economics refers to the difference in the price and the cost of a good that is able to sale. Moreover, the "markup" is added into the total cost of the production of the good in order to obtain a profit for the sale of that good, so therefore that it implicates the percentage that the producer gains for selling his product to a consumer. So that is why this concept is understood as that difference comprehended between the sale price and the cost of the good produced.