True / False / UncertaintyWith Explanation

True, False or Uncertain and explain why. All points will be awarded based on the quality of your explanation. 1. A producer will determine whether to operate or not by considering her short-run average variable costs, her profit level by considering her short-run average total cost, and her optimal level of output by considering her short-run marginal cost. 2. Import ta riff can be implemented to protect domestic sellers without making any loss to the other parts of the economy. 3. A monopoly has no competition, so it can charge whatever price it wishes and it always enhances profit by increasing its price. 4. It costs more to increase output in the short-run than in the long-run. 5. If the market supply curve is vertical, there is no the deadweight loss of a sales tax or a subsidy. 6. A perfect price discrimination increases economic efficiency as compared to simple monopoly