(a) Natural Language Processing
Alexa and Siri are voice assistants that leverage NLP to understand natural speech and execute tasks efficiently.
Source: Chapter 6, Section 6.2 – Applications of Natural Language Processing
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The passage explicitly states: "Hey Alexa, play some music" and "Hey Siri, what's the weather today" as examples under Voice Assistants, which is listed as an application of Natural Language Processing. In MCQs, always look for the exact term used in the textbook against the given examples.