A mortgagor's right to bring himself out of default by paying money owed to the lender is:

The correct choice is the equity of redemption. This term refers to the right of a mortgagor (the borrower) to reclaim their property after defaulting on a mortgage by paying off the outstanding debt. Essentially, it allows the borrower to "redeem" their property before it is taken through foreclosure by satisfying their financial obligations to the lender.

The equity of redemption is an essential protection for homeowners, ensuring they have a chance to save their property from foreclosure as long as they can pay the total amount owed. It signifies that even if a borrower is in default, they still retain an interest in their property and can recover it by fulfilling their financial commitments.

The other choices—assumption of mortgage, amortization of mortgage, and strict foreclosure—refer to different concepts within mortgage finance and do not accurately describe the right of a borrower to pay off their debt and regain their property after default. Assumption of mortgage involves taking over someone else's mortgage, amortization deals with the gradual repayment of a debt through scheduled payments, and strict foreclosure is a process that allows a lender to take ownership of property without a public sale.