Explanation

Amazon Comprehend is the correct AWS service for sentiment analysis because:

• Amazon Comprehend is a natural language processing (NLP) service that uses machine learning to find insights and relationships in text
• It can analyze text to determine sentiment (positive, negative, neutral, or mixed)
• It's specifically designed for text analysis tasks like sentiment analysis, entity recognition, and language detection

Why not the other options:

• Amazon Textract: Used for extracting text and data from scanned documents, not sentiment analysis
• Amazon Translate: Used for language translation between different languages
• Amazon Rekognition: Used for image and video analysis, not text sentiment analysis

For analyzing customer service email messages to determine positive or negative sentiment, Amazon Comprehend is the appropriate AWS service.