The correct answer is: A. Dual aspect concept.
The dual aspect concept states that every business transaction has two aspects: a debit and a credit. The debit side of a transaction represents an increase in an asset or a decrease in a liability, while the credit side of a transaction represents an increase in a liability or a decrease in an asset.
Capital is treated as a liability because it represents a claim on the assets of the business. The owners of a business have a claim on the assets of the business, and this claim is represented by the capital account. The capital account is a liability because it represents a debt that the business owes to the owners.
The other options are incorrect because they do not explain why capital is treated as a liability.
- The money measurement concept states that only transactions that can be measured in monetary terms should be recorded in the financial statements. This concept does not explain why capital is treated as a liability.
- The matching concept states that expenses should be matched with the revenues that they generate. This concept does not explain why capital is treated as a liability.
- The entity concept states that a business is a separate entity from its owners. This concept does not explain why capital is treated as a liability.