What is the optimal option to give dealer managers visibility to customer cases only raised by their service agents?

Universal Containers (UC) is a fast-growing company that sells containers globally. It has thousands of dealerships throughout the world where local dealers service containers. UCimplemented a new Partner Community for its dealers. Each dealership has a dealer manager who manages the service agents. The community-sharing model is private.

What is the optimal option to give dealer managers visibility to customer cases only raised by their service agents?
A . Change external organization-wide default of case object to public read only.
B. Create a sharing rule to share cases created by service agents with their dealer manager.
C. Using the role hierarchy, the cases raised by service agents will be visible to their relevant dealer managers.
D. Create a sharing set to share cases created by service agents with their dealer manager.

Answer: D