Leveraging the purchase of a real estate investment will enhance the before tax IRR if the following is true?

a. The effective borrowing cost is greater than the unlevered IRR.

b. When the annual rate of the mortgage is greater than the unlevered IRR.

c. When the annual rate of the mortgage is less than the unlevered IRR.

d. The effective borrowing cost is less than the unlevered IRR.

e. None of the above