The correct answer is D. Goodwill.
Current assets are assets that are expected to be converted into cash or used up within one year or the operating cycle, whichever is shorter. They include cash, accounts receivable, inventory, and short-term investments.
Goodwill is an intangible asset that arises from the acquisition of a business. It is the difference between the purchase price of the business and the fair value of its net assets. Goodwill is not a current asset because it is not expected to be converted into cash within one year or the operating cycle.
Debtors are amounts owed to a company by its customers. Bills receivable are amounts owed to a company by its suppliers for goods or services that have been delivered but not yet paid for. Stock is the value of the goods that a company has on hand for sale. These are all current assets because they are expected to be converted into cash within one year or the operating cycle.