Which essential element is needed to perform events analysis and correlation?

Which essential element is needed to perform events analysis and correlation?

A.
elimination of all the true positive events

B.
implementation of the same IPS and firewall policies throughout the network

C.
time synchronization between all the devices

D.
implementation of a centralized provisioning system, such as Cisco Security Manager

E.
implementation of different security controls and platforms when using the defense-in-depth
approach