D. Safe Object The Safe Object check applies to server responses from a protected application. It uses user-configurable regular expressions to identify and protect sensitive information such as customer numbers or order numbers, by blocking the response, masking the protected information, or removing the protected information from the response before sending it to the user.

The Safe Object check provides user-configurable protection for sensitive business information, such as customer numbers, order numbers, and country-specific or region-specific telephone numbers or postal codes

I would say it is D: https://docs.citrix.com/en-us/citrix-adc/current-release/application-firewall/dataleak-prevention/safeobject-check.html