When configuring Appointments, which categories are provided as system defaults and cannot be deleted?

According to the SAP Service Cloud Version 2 Feature Scope Description1, Appointments are used to schedule and track activities related to service requests, such as meetings, tasks, phone calls, and visits. The system provides four default categories for Appointments: Meeting, Task, Outbound Phone Call, and Inbound Phone Call. However, only Meeting and Task categories are mandatory and cannot be deleted. The other two categories can be deactivated or deleted by the administrator if they are not needed. Therefore, the correct answers are A and C. References = SAP Service Cloud Version 2 Feature Scope Description, page 28.