Which one of the following is not an essential element of a Mortgage as defined under Section 58(a) of…

Under section 58(a) of the Transfer of Property Act, 1882, a mortgage is the transfer of an interest in specific immovable property for the purpose of securing the payment of money advanced or to be advanced by way of loan, an existing or future debt, or the performance of an engagement which may give rise to a pecuniary liability. An actual transfer is required, so "There must be promise to transfer of interest" is not an element; a mere promise to transfer does not create a mortgage.