Explanation:

- Option 1: AR=MR

- Average Revenue (AR) equals Marginal Revenue (MR) typically in perfect competition.

- Does not necessarily determine profit maximization directly.

- Option 2: MR=MC

- Profit is maximized when Marginal Revenue (MR) equals Marginal Cost (MC).

- At this point, the difference between Total Revenue (TR) and Total Cost (TC) is also maximized.

- Correctly identifies the condition for optimal profit.

- Option 3: MR=AC

- Implies marginal revenue equals average cost.

- Not typically a profit-maximizing condition.

- Option 4: MC=AC

- Marginal Cost (MC) equals Average Cost (AC) at the minimum point of AC.

- Not directly related to maximization of the difference between TR and TC.

Option 2: MR=MC