Which accounting entity concept specifies that a business' transactions must be separate from its owners' personal transactions?

The entity concept is fundamental in accounting as it establishes that a business is viewed as a separate legal entity from its owners or shareholders. This means that the financial activities and transactions of the business must be recorded and reported distinctly from those of the owners. This separation ensures clear accountability and provides a true representation of the business's financial position and performance.

By adhering to this concept, financial statements reflect only the business's assets, liabilities, income, and expenses, without any blending of personal transactions of the owners. This is essential for various reasons, including compliance with legal and tax regulations, as well as maintaining transparency for stakeholders.

The other concepts mentioned, such as the partnership and sole proprietor concepts, relate specifically to the structure of ownership rather than directly addressing the separation of personal transactions from business transactions on financial statements. The income statement concept focuses on measuring and reporting the profitability of an entity over a specific period and does not deal with the entity's separateness from its owners' personal financial activities. Therefore, the entity concept is the correct answer as it encapsulates this crucial principle of separate financial accounting.