The Red River Division of Alto Company Produces and Sells

The Red River Division of Alto Company produces and sells bags of pottery clay that can either be sold to outside customers or transferred to the White Mountain Division of Alto Company. The following data are available from the last year:
By selling to the White Mountain Division, the Red River Division will avoid £3 per bag in selling costs.
-If Red River can sell 15,000 bags annually to outside customers, according to the formula in the text, what is the lowest acceptable transfer price from the viewpoint of the selling division

A) £20
B) £16
C) £11
D) £14