In Dynamics 365 Customer Service, the system is designed to automatically apply a default entitlement to a case at specific trigger points. The primary trigger is upon the creation of a new case for a customer who has a default entitlement configured. Additionally, the system re-evaluates and applies the appropriate entitlement if key associative fields on an existing case are modified. These fields are the Customer (Account or Contact) and Product, as changing them may alter which entitlement is applicable.

C. Update the description field on an existing case.

Updating informational text fields like the description does not trigger the business logic that governs entitlement application.

D. Add an activity to an existing case.

Adding related records such as activities (emails, phone calls) does not trigger a re-evaluation of the entitlement on the parent case record.

1. Microsoft Learn. (2023). Automatically apply entitlements to cases. Dynamics 365 Customer Service documentation.

Reference: In the "How entitlements are automatically applied" section

the documentation states

"An entitlement can be automatically applied to a case when a case is created or when the customer

contact

or product field of the case is updated." This directly supports options A and B as the correct triggers.