Which of the following statements is correct? Question 6Answer a. Opportunity cost is the monetary cost of choosing an action over an alternative. b. Indifference curves show all combination of goods that are within the budget of the consumer. c. The optimal choice for a consumer who is maximizing her utility would equate marginal rate of substitution and marginal rate of transformation. d. Because of scarcity of resources, average income and standard of living have declined over time