Which Statement Best Explains the Retail Inventory Method

Which statement best explains the retail inventory method?

A) A method for estimating cost of goods sold by applying an average gross margin to the amount of sales recorded in a period.
B) A method that assigns costs to inventories and cost of sales based on actual costs of each item.
C) A method of estimating the cost of ending inventory by applying an average sales margin to the retail price of products.
D) This method is least appropriate for inventory items that are not distinguishable from one another.