hich of the following statements is true? Select all correct answers. [NOTE: For this question type incorrect answers will deduct some or all points earned by correct answers, depending on how many of each are selected. If you are in doubt about a possible answer, it may be a better idea to leave it unselected.] Group of answer choices Firms operating in perfect competition face downward-sloping demand curves. Firms that make and sell differentiated goods face downward-sloping demand curves. Firms that make and sell differentiated goods produce at the point where their marginal cost is at the market price (or as close as possible to the market price without going over it). Firms operating in perfect competition produce at the point where their marginal cost is at the market price (or as close as possible to the market price without going over it). The sum of consumer surplus and producer surplus will be maximized when there are many firms making and selling essentially indistinguishable goods in perfect competition with one another. The sum of consumer surplus and producer surplus will be maximized when there is a single firm making and selling a differentiated good