Which Amazon service can be used to detect potentially fraudulent online activities?

Amazon Fraud Detector is specifically designed to identify potentially fraudulent online activities. It uses machine learning models to analyze patterns and trends in user behavior, transactions, and other relevant data to assess the likelihood of fraud. By leveraging pre-built models as well as the ability to create custom models tailored to an organization's unique needs, it provides a robust solution for detecting and preventing fraud in real-time.

The focus of this service is solely on fraud detection, which sets it apart from the other options. For instance, Amazon Rekognition is a computer vision service used primarily for image and video analysis, like facial recognition or object detection. Amazon Mechanical Turk facilitates human intelligence tasks and is not related to fraud detection. Meanwhile, Amazon SageMaker is a comprehensive platform for building, training, and deploying machine learning models but does not focus specifically on fraud detection. Consequently, for the purpose of detecting fraudulent activities online, Amazon Fraud Detector is the most appropriate choice.