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