What AWS service uses natural language processing to extract insights from documents?

Amazon Comprehend is the correct choice because it is an AWS service specifically designed to analyze text using natural language processing (NLP). This service helps in automatically extracting insights such as entities, key phrases, language, sentiment, and more from unstructured text documents. It employs machine learning models that can understand and interpret the nuances of natural language, making it an effective tool for businesses needing to extract meaningful data from their documents and customer communications.

Amazon Lex, while also working with natural language, focuses on building conversational interfaces, such as chatbots, rather than extracting insights from documents.

Amazon Rekognition is centered around image and video analysis, using deep learning to identify objects, people, and activities in multimedia content. This makes it unsuitable for document insight extraction.

AWS DeepLens is a deep learning-enabled video camera that allows for real-time computer vision applications but does not specialize in text analysis or natural language processing.

Therefore, Amazon Comprehend stands out as the most relevant service for extracting insights from documents using NLP capabilities.