Could you please explain why option B C & D are incorrect?

1. Adams Company is a retailer and uses a perpetual inventory system. Which statement is correct? A. Returns of merchandise inventory by Adams Company to a manufacturer are credited to merchandise inventory. B. Freight paid to get merchandise inventory to Adams Company's store is debited to Freight Expense. C. A return of merchandise inventory by one of Adams Company's customers is credited to merchandise inventory. D. Discounts taken by Adams Company's customers are credited to merchandise inventory