Which two elements are valid design choices?

A pega application has cases that represent customer accounts each with many members. When a member of a customer account registers with the application through an offline component, a related registration transaction is recorded. An advanced agent updates the customer account cases with new members. The application is running in a multimode system and advanced agents are enabled on all nodes.

Which two elements are valid design choices? (choose two)
A . Use the optimistic locking option on the case types.
B . Create a Registration subcase configured to run in offline mode.
C . Leverage the default object lock contention requeuing capability.
D . Override DetermineLockString to use .AccountID instead of .pyID as the lock string.

Answer: B C