What are two ways the Salesforce Admin should fulfill these requirements?

Universal Containers is building a Community to drive channel sales. They have 2,000 partner accounts.

The high-level capabilities for their partners are as follows:

– Partner users should NOT be able to access accounts and cases that they do NOT have access to.

– A Partner user must be able to create cases for all accounts in their account hierarchy irrespective if they are parent of child account.

– Partner users must be able to collaborate within the private groups they are members of.

What are two ways the Salesforce Admin should fulfill these requirements? Choose 2 answers.
A . Create a Criteria-based Sharing Rule with read/write access on the Account and Case Object.
B . Set External User Organisation Wide Defaults to Private on the Account and Case Object.
C . Configure an Owner-based Sharing Rule on the Account and Case Object.
D . Develop an Apex Managed Sharing Rule on the Account and Case Object.