A customer has placed four Network Intrusion Prevention System devices in different groups representing remote offices. The groups are contained by a parent group. A Security Events policy has been…

A customer has placed four Network Intrusion Prevention System devices in different groups representing remote offices. The groups are contained by a parent group. A Security Events policy has been created and must be deployed to the four devices. What is the minimum number of groups the policy must be deployed to so all devices are covered?