Concept:A mortgagor is the borrower who pledges property, such as a building, as security for a loan.Explanation:In a mortgage transaction, the person who owns the building and offers it as collateral is the borrower. This borrower is called the mortgagor.The lender who receives the building as security is known as the mortgagee.A trustee manages property on behalf of others, and a guarantor promises to repay the loan if the borrower defaults.Therefore, the person giving his building as security is the mortgagor.Answer:C. mortgagor