Which of the Following General Assumptions Underlie the Retail Inventory

Which of the following general assumptions underlie the retail inventory method?

A) The inventory is sufficiently homogeneous to have the same markup and the cost-to-retail ratio changes inversely to the costs of purchases.
B) The inventory is sufficiently homogeneous to have the same markup and the cost-to-retail ratio changes relative to the costs of purchases.
C) The inventory is sufficiently homogeneous to have a different markup and the cost-to-retail ratio changes inversely to the costs of purchases.
D) The inventory is sufficiently homogeneous to have a different markup and the cost-to-retail ratio changes relative to the costs of purchases.