When banks make new loans, the effect on reserves is the same as

Which of the following statements is true?

a. The law of diminishing returns states that beyond some point the marginal product of a variable resource continues to rise. b. The marginal product is the change in total output by adding one additional unit of a fixed input. c. Fixed costs are costs which vary with the output level. d. When marginal productivity of a variable input is falling then marginal costs of production must be rising. e. When marginal cost is below average cost, average cost rises; when marginal cost is above average cost, average cost falls.

Although patents are a ________, they also provide ________.

A. barrier to entry; for free entry of new firms B. collusive agreement; for free entry of new firms C. collusive agreement; an incentive for invention and innovation D. barrier to entry; an incentive for invention and innovation