If a firm charges $9.00, it can sell only three units of its product. Lowering its price to $8.00 allows it to sell four. The marginal revenue of the fourth unit is: $9.00 $8.00 $6.00 $5.00 Choose the most correct answer by clicking a button, or by typing a letter from the keyboard and pressing the tab key. Answer the next question using this table: Quantity Marginal Revenue First $12 Second $10 Third $8 The total revenue for selling three units of output will be: $2. $18. $24. $30. Choose the most correct answer by clicking a button, or by typing a letter from the keyboard and pressing the tab key.