Which two things should UC keep in mind when setting up partner roles?

Universal Containers (UC) is planning to create a portal for its global partner network.

Users will be assigned a Partner Community license and a role.

Which two things should UC keep in mind when setting up partner roles? Choose 2 answers
A . Role Hierarchy can only be used if all objects have external OWD set to Private.
B. The default limit for the number of roles for portals is 50,000 per org.
C. Unused roles can be deleted.
D. Once created, roles cannot be deleted.

Answer: B,C