Final answer:
The correct answer is option 4. In the given options, the situation represented by zero profit is 'a $4 profit'. Zero profit occurs when the revenue earned by a business is equal to the cost incurred.
Step-by-step explanation:
In the given options, the situation represented by zero profit is 'a $4 profit'. Zero profit occurs when the revenue earned by a business is equal to the cost incurred.
In this case, a $4 profit indicates that the revenue generated is exactly equal to the cost incurred. Therefore, the business is not making any additional profit.
This can be represented by the equation:
Revenue - Cost = Profit
$4 - $0 = $4
Since the profit is not negative and not greater than zero, it is equal to zero.