Error Analysis: A store is instructed by corporate headquarters to put a markup of 67​% on all items. An item costing ​$6 is displayed by the store manager at a selling price of ​$4. As an​ employee, you notice that this selling price is incorrect. Find the correct selling price. What was the​ manager's likely​ error?

Part 1: The correct selling price is ​(Round to the nearest dollar as​ needed.)
Part 2: What was the​ manager's likely​ error?

A. The manager set the selling price at the markup.
B. The manager subtracted the markup from the cost instead of adding it.
C. The manager set the selling price at the cost.
D. The manager added the markup to the cost instead of subtracting it.