Explanation

Amazon Comprehend is the correct AWS service for this use case because:

• Sentiment Analysis: Amazon Comprehend can analyze text to determine the emotional tone (positive, negative, neutral, or mixed) of customer reviews
• Key Phrase Extraction: It can automatically identify and extract key topics, phrases, and entities mentioned in the text
• Natural Language Processing: As a managed NLP service, it's specifically designed for text analysis tasks like this
• No ML Expertise Required: Unlike Amazon SageMaker which requires machine learning expertise, Comprehend provides pre-trained models that work out-of-the-box

Why not the other options:

• Amazon Rekognition: Primarily for image and video analysis, not text
• Amazon Transcribe: Converts speech to text, but doesn't analyze sentiment or topics
• Amazon SageMaker: Requires building custom ML models, which is overkill for this pre-built use case

Amazon Comprehend is the most appropriate service for analyzing customer reviews to detect sentiment and key topics without requiring machine learning expertise.