A firm will maximize profit by producing that level of output at which

1. Total revenue equals total cost

2. The additional revenue from the last unit sold equals the additional cost of the last unit

3. The additional revenue from the last unit sold equals the additional cost of the last unit, and the total revenue exceeds total cost by the largest amount

4. The additional revenue from the last unit sold exceeds the additional cost of the last unit by the largest amount

5. Total revenue exceeds total cost by the largest amount