Salesforce's secure MFA guidance is based on two independent factors, not simply any second code that can be sent to the user. Strong MFA methods include possession-based authenticators and standards-compliant mechanisms such as security keys, approved authenticator apps, and trusted third-party SSO solutions that themselves enforce strong MFA. Lightning Login is also treated as a passwordless, device-based secure approach in the Salesforce ecosystem. By contrast, SMS and email verification do not meet Salesforce's general MFA requirement for secure user-interface logins in the same way. The architecture point is that Salesforce distinguishes between convenience verifications and strong authentication factors. For compliance- driven MFA, architects should choose the methods Salesforce classifies as high-assurance. This is why options A, B, D work together as the correct solution.