MFA (Multi-Factor Authentication) requires factors from different categories:

Something you know → Password, PIN

Something you have → Smart card, hardware (hard) token

Something you are → Biometric

The correct second factor is a hard token.

A. PIN = something you know (same factor as password).

B. Favorite color = knowledge-based, same factor as password.

D. Mother’s maiden name = weak knowledge-based, same factor as password.

References (CompTIA Network+ N10-009):

Domain: Network Security — Authentication methods, MFA categories.