Answer: B) rise
Step-by-step explanation:
The real rental price of capital refers to the cost of borrowing capital which is the interest payment on the capital less the capital gains made. As a result it is equal to the marginal product of capital which shows how much extra, a unit of capital enables the entity to produce.
Therefore, if marginal product of capital rises, as is the case in the question, so will the real rental price of capital.