Correct Option: D

The interest rate is the cost of demanding or borrowing loanable funds. Alternatively, the interest rate is the rate of return from supplying or lending loanable funds. The demand for loanable funds takes account of the rate of return on capital. The rate of return on capital is the additional revenue that a firm can earn from its employment of new capital. This additional revenue is usually measured as a percentage rate per unit of time, which is why it is called the rate of return on capital. Firms will demand loanable funds as long as the rate of return on capital is greater than or equal to the interest rate paid on funds borrowed. In case of increase in interest rate, retrun on capital decreases.