What are common signs that a system has been compromised or hacked?

What are common signs that a system has been compromised or hacked? (Choose three.)

A.
Increased amount of failed logon events

B.
Patterns in time gaps in system and/or event logs

C.
New user accounts created

D.
Consistency in usage baselines

E.
Partitions are encrypted

F.
Server hard drives become fragmented

Explanation: