A) a cryptographic mechanism used to verify message integrity and the signer's possession of a private key
B) authentication requiring evidence from two or more different factor categories
C) an update intended to fix vulnerabilities or security weaknesses in software
D) a social-engineering technique that tempts a victim with something attractive to trigger unsafe action
Answer: B
Explanation: Multi-factor authentication refers to authentication requiring evidence from two or more different factor categories. The other choices describe different concepts from the same topic.