The correct answer should be B) Amazon Polly, not A.

Explanation:

• Amazon Polly is AWS's text-to-speech service that converts text into lifelike speech in multiple languages and voices. It's specifically designed for applications that need to read out text in natural-sounding speech.
• Amazon Transcribe (option A) is for speech-to-text conversion, not text-to-speech.
• Amazon Translate (option C) is for language translation between text.
• Amazon Comprehend (option D) is for natural language processing and text analysis.

For a mobile app that needs to read notifications in natural-sounding speech across multiple languages, Amazon Polly is the appropriate AWS service.