A third-party vendor assumes roles in many customer accounts. A customer wants to mitigate the confused deputy risk for its role. Which trust condition is most appropriate?

1. Require the vendor-assigned unique external ID along with the trusted vendor principal.
2. Use the external ID as a secret password that replaces the vendor principal restriction.
3. Allow the vendor root password to be embedded in the trust policy.
4. Trust every AWS principal if the role name is difficult to guess.