Which of the following is an example of two factor authentication?

Both a PIN and a birth date are 'something you know' factors, placing them in the same authentication category and making this single-factor authentication with two knowledge-based credentials.

A username and password are both 'something you know' factors and together represent standard single-factor authentication, not two distinct factor types.

A digital certificate and a hardware token are both classified as 'something you have' possession factors, meaning they belong to the same authentication category and do not constitute two separate factors.

A fingerprint belongs to the 'something you are' category (biometric factor), while a Smartcard ID belongs to the 'something you have' category (possession factor). Because these two credentials come from two distinct authentication factor categories, this combination satisfies the definition of two-factor authentication and provides stronger assurance than using multiple items from the same category.