Comprehensive and Detailed Explanation From Exact Extract:

The problem is the detection of secrets (sensitive data patterns) within the environment variables of deployed resources (Cloud Functions) in a timely, automated manner.

Sensitive Data Protection (SDP), formerly Cloud DLP, is the purpose-built Google Cloud service for scanning and classifying sensitive data patterns. It can be configured to scan code, configuration, or environment variables and integrate its findings directly with Security Command Center (SCC).

Extracts:

"Sensitive Data Protection provides highly configurable, automated detection of sensitive data, including API keys, passwords, and other credentials, using both pre-built and custom infoTypes." (Source 8.1)

"SDP can be integrated with Cloud Functions and other resource configurations to scan environment variables or configuration files for secrets. Violations can be automatically routed to Security Command Center as findings." (Source 8.2)

Option D (DAST) scans the application code or running application logic, but the requirement specifies the secrets are in the environment variables, which are part of the configuration/deployment metadata, making SDP the correct detection tool.