Grey Manufacturing Had the Following Transaction

Grey Manufacturing had the following transaction:
.Grey received an order to sell inventory with a cost of $50,000, and debited Accounts Receivable and credited Sales. The goods were shipped to the customer on December 31, 2017, and received on January 2, 2018.
If the terms of the sale were FOB shipping point and Grey included all these items in its ending inventory of 12/31/17, which of the following is the best statements regarding this treatment?

A) Grey made no mistake and rightfully included the items in its inventory until January 2, 2018.
B) Grey made a mistake and wrongly understated ending inventory.
C) Grey made a mistake and wrongly understated Cost of Goods Sold.
D) Grey made a mistake and wrongly understated Retained Earnings.