Final answer:
A first mortgage is typically associated with the lowest interest rate because it is secured by the property and has priority over other claims in a default situation, reducing the risk to the lender.
Step-by-step explanation:
The type of security typically associated with the lowest interest rate is a first mortgage. A first mortgage is a primary loan taken out by a borrower to purchase a property and holds priority over other claims against the property in the event of default.
Other options such as a second mortgage, personal loan, or credit card debt generally carry higher interest rates because they present a higher risk to the lender. With a second mortgage, the lender is in second position to claim assets in a default situation, making it riskier than the first mortgage. Personal loans and credit card debt are unsecured, which means there's no collateral for the lender to fall back on, which also leads to higher interest rates.