While Both Use a Mathematical Calculation, There Is an Important

While both use a mathematical calculation, there is an important different between "markup" and "margin." Which of the following is correct?

A) Markup is a percentage added to the cost of the product and margin is a percentage of the sales price left over after paying for the cost of the product.
B) Margin is a percentage added to the cost of the product and markup is a percentage of the sales price left over after paying for the cost of the product.
C) Markup can only be calculated based on selling price, while margin is only calculated based on wholesale price.
D) Margin is calculated based on variable costs while markup is based on fixed costs.