Explanation
B: To use anything other than common capabilities in finance and operations apps, users must be assigned to security roles. You can assign users to roles automatically, based on rules and business data, exclude users from automatic role assignment, or add users to roles manually.
C: You can set up rules to separate tasks that must be performed by different users. This concept is named segregation of duties.
Reference:
https://docs.microsoft.com/en-us/dynamics365/fin-ops-core/dev-itpro/sysadmin/tasks/assign-users-security-roles
https://docs.microsoft.com/en-us/dynamics365/fin-ops-core/dev-itpro/sysadmin/tasks/set-up-segregation-duties