An unsecured loan is defined as a debt whose repayment is not guaranteed by collateral or a pledge of something of value. Therefore, the correct response in your options would be the first one, although the wording does not directly match.
To clarify: an unsecured loan is typically not backed by any collateral, meaning that if the borrower defaults, the lender has no specific asset to claim. Examples of unsecured loans include personal loans and credit card debt.
None of the options provided (a payday loan, a mortgage, or a car lease) fit the definition of an unsecured loan. A payday loan may be unsecured, but a mortgage is secured by real estate, and a car lease is typically considered a secured transaction as well.