You are configuring network connections to your database instance.
What does each network group represent?
A.
It is used to allow unrestricted communication among some of your DBaaS instances by using a set of defined policies and access rules.
B.
It is used to define load balancing and failover configurations between RAC database instances.
C.
It is used to define network connections to the Pluggable Databases (PDBs) within a Container Database.
D.
It is used to manage the connections between your external application servers (application servers that you currently use in your business environment) and
your DBaaS instances.
Explanation:
Network groups provide a method for VMs to be grouped together for communications and firewall rules. You can define network groups to allow VMs within a
group to communicate with each other, while also preventing those VMs from communicating outside the group.
Note:
Access rule. Access rules define the permitted paths of communication for VMs that are within a network group. You can define an access rule to enable a specific
path of communication between two network groups, or between a network group and a specified list of IP addresses.
http://www.oracle.com/webfolder/technetwork/tutorials/obe/cloud/dbaas/OU/IntroDBaaS/ConfiguringNetworkSettings/
ConfiguringNetworkSettings.html#section2s2