Final answer:
The purchase of merchandise is the transaction related to merchandise inventory that is recorded in books.
Step-by-step explanation:
About merchandise inventory, the transaction that is recorded in books is the purchase of merchandise. When a company purchases inventory, it is recorded in the books as an increase in inventory and a decrease in cash or accounts payable.
The sale of merchandise is also recorded in books, but it is not directly related to merchandise inventory. When a company sells inventory, it is recorded as a decrease in inventory and an increase in accounts receivable or cash.
The return of merchandise and depreciation of merchandise do not directly affect the inventory account, so they are not recorded as transactions related to merchandise inventory.