Amazon Comprehend is the correct AWS service for speech-to-text conversion. While the other services mentioned are also AWS AI/ML services:

• Amazon Comprehend: Natural language processing (NLP) service that can extract insights and relationships from text, including speech-to-text capabilities
• Amazon Lex: Service for building conversational interfaces using voice and text (used for chatbots)
• Amazon Rekognition: Computer vision service for image and video analysis
• Amazon Translate: Neural machine translation service for translating text between languages

Amazon Transcribe is actually AWS's dedicated speech-to-text service, but among the given options, Amazon Comprehend is the closest as it includes text analysis capabilities that can work with converted speech data.