Final answer:
The correct answer is accounts receivable. Current assets are assets that are expected to be converted into cash or used up within one year or one operating cycle, whichever is longer. Buildings, long-term investments, and patents are not classified as current assets.
Step-by-step explanation:
The correct answer is c) Accounts receivable.
Current assets are assets that are expected to be converted into cash or used up within one year or one operating cycle, whichever is longer. Accounts receivable is considered a current asset because it represents the money owed to a business by its customers for sales made on credit.
Buildings, long-term investments, and patents are not classified as current assets. Buildings are typically classified as long-term assets, long-term investments are classified as non-current assets, and patents are classified as intangible assets.