Answer:
The correct answer is Option C.
Step-by-step explanation:
Economic profit is simply the difference between the total revenue generated from the sale of an output minus the opportunity cost and all costs used in the production of that output.
The costs used in the production of that output are regarded as explicit costs.
Opportunity cost is subjective and judgemental and usually determined by management.
Based on the question, the Economic cost = Total revenue - Total variable cost - Total fixed cost
Economic cost = $90,000 - $30,000 - $40,000 = $20,000