To strictly enforce compliance and prevent a user from proceeding with an action that violates a limit, the Limit Enforcement Type on the Product Limit record must be set to 'Error'. This configuration will display an error message and prevent the user from saving the record (e.g., a Call Report where samples are recorded) if the defined annual or per-visit limit is exceeded. This ensures the distribution is blocked as required, maintaining regulatory compliance.

A. Threshold is a concept related to a limit's value, but it is not a valid picklist value for the Limit Enforcement Type field.

C. Setting the enforcement type to 'Warning' would display a notification to the user but would still allow them to save the record and exceed the limit.

1. Salesforce Help. (2023). Set Up Product Limits for Sampling. "In the Limit Enforcement Type field, select Error to show an error message and prevent users from saving the record. Select Warning to show a warning message and let users save the record."

2. Salesforce Life Sciences Cloud Administrator Guide. (2023). Configure Sample Management. Section: Product Limits. This section details the available enforcement types, specifying that 'Error' provides a hard stop to prevent violations.