Which of the following statements is true of mortgages?
a. The recording statutes and the priority rules do not apply to mortgages.
b. The extinction of a mortgage by foreclosure destroys the debt that was secured by the mortgage.
c. An unrecorded mortgage is invalid among the parties.
d. Under title theory, the mortgagee has the right, upon foreclosure of a property, to possession and rents on that property.