Which mortgage type includes the secured movable personal property as collateral?

The correct choice is the chattel mortgage, as it specifically involves movable personal property as collateral, unlike traditional mortgages which typically secure real estate. Chattel mortgages allow the borrower to use personal property such as vehicles, equipment, or other movable assets to secure financing, making it a flexible option for those who need to finance these types of assets. This structure provides lenders with a security interest in the movable property, similar to how a conventional mortgage or FHA mortgage secures real property.

In contrast, a conventional mortgage and an FHA mortgage are both designed to secure real estate as collateral, focusing on immovable property like homes and land. A mortgage buy-down, on the other hand, refers to a financing strategy used to lower interest rates for a borrower, but does not pertain to the nature of collateral secured. Therefore, the unique property of chattel mortgages pertaining to movable assets clearly distinguishes it as the correct answer in this context.