Which of the following is NOT a branch of AI?

Biometrics is not considered a branch of artificial intelligence. It primarily involves the measurement and analysis of unique physical or behavioral characteristics, such as fingerprints, facial recognition, or voice patterns, to identify individuals. While biometrics can leverage AI technologies and algorithms to enhance accuracy and efficiency, it is fundamentally a field focused on personal identification rather than the core functionalities of AI.

In contrast, the other fields mentioned—machine learning, natural language processing, and robotics—are integral branches of AI. Machine learning involves algorithms that allow computers to learn from and make predictions based on data. Natural language processing enables machines to understand and interpret human language, bridging the gap between human communication and computer understanding. Robotics involves the design and use of robots that can perform tasks, often utilizing AI to enhance their capabilities. Thus, biometrics stands apart as it does not directly represent an area of artificial intelligence in the same way these other fields do.