What must a lender do for their rights to be enforceable against third parties?

For a lender's rights to be enforceable against third parties, the lender must both attach and perfect the security interest. "Attachment" occurs when the lender has a security agreement with the borrower, the borrower has rights in the collateral, and the lender gives value. This creates the security interest. However, to ensure that this interest is enforceable against third parties—such as creditors or subsequent purchasers—the lender must also "perfect" the security interest.

Perfection typically involves taking additional steps to provide public notice of the security interest. This is usually done by filing a financing statement with the appropriate state office, which puts third parties on notice that the lender has a security interest in the specific collateral. By achieving perfection, the lender secures priority over competing claims to the collateral, enhancing their ability to enforce the security interest in case of debtor default.

In summary, both attachment and perfection are critical steps in establishing the enforceability of a lender's rights against third parties, which makes this the correct choice. Options that suggest different combinations of steps would not adequately establish enforceability in the same way that attachment and perfecting the interest do.