Which option best supports secure access control?

• A. Single-factor password
• B. Share passwords with colleagues
• C. Email verification only
• D. Multi-factor authentication

Answer: (D)

Strengthening access control comes from using multiple authentication factors rather than just one credential. Multi-factor authentication adds at least two independent evidence types for proving identity, typically something you know (a password), something you have (a hardware token or mobile device), or something you are (biometrics). Because the factors are independent, compromising one does not automatically grant access, so even if a password is stolen, the attacker would still need the second factor to log in. This dramatically reduces the risk of unauthorized access in common attack scenarios like phishing or credential reuse.

Relying on a single-factor password leaves a single point of failure; if the password is leaked, an attacker can get in. Sharing passwords with colleagues breaks individual accountability and increases the chance that credentials are exposed. Email verification only provides a single step and can be intercepted or redirected, and it doesn’t add a true second factor. So multi-factor authentication best supports secure access control.