Which Google Cloud service should be used to automatically detect and redact sensitive information in medical reports before processing?

The Cloud Data Loss Prevention (DLP) API is specifically designed to help organizations automatically discover, classify, and redact sensitive information such as personally identifiable information (PII) or health information in unstructured data sources, which includes medical reports. This service allows users to implement policies to ensure that sensitive data is not inadvertently exposed during processing or analysis.

With the capability to identify various types of sensitive data, the DLP API leverages machine learning and predefined dictionaries to recognize complex data types specific to healthcare, such as Social Security numbers, patient health information, and more. It provides features to redact or mask this sensitive information to enhance data security and compliance with regulations.

In contrast, the other services listed do not serve the same purpose. Pub/Sub is focused on message queuing and real-time data ingestion, while Cloud Storage is primarily for storing and retrieving files without specialized features for data sensitivity detection. BigQuery Data Transfer Service is used to automate data ingestion into BigQuery but does not address the needs of sensitive data identification and redaction. Thus, the DLP API stands out as the appropriate choice for handling sensitive information in medical reports.