Suppose the total revenue function for a blender is R(x) = 20x- 0.0lx2 dollars where x is the number of units sold. What is the marginal revenue when 1000 units are sold, and what does it mean? 10. Selling an additional unit when 1000 have been sold increases revenue by $10. 21. Selling an additional unit when 1000 have been sold increases revenue by $21. 20. Selling an additional unit when 1000 have been sold increases revenue by $20. 11. Selling an additional unit when 1000 have been sold increases revenue by $11. 0. Selling an additional unit when 1000 have been sold increases revenue by $0. None of these