Question: Under what condition(s) will a PCEF (Policy and Charging Enforcement Function) allow a service data flow under charging control to pass through the Gateway for online charging?
Option 1: If there is a corresponding active PCC rule.
Option 2: If the OCS has authorized the applicable credit with that Charging key, but no active PCC rule exists.
Option 3: If the service data flow is not subject to any policy control.
Option 4: If there is a corresponding active PCC rule and the OCS has authorized the applicable credit with that Charging key.
Explanation: For a service data flow under charging control, especially for online charging, two crucial conditions must be met for the PCEF to allow the flow through the Gateway: The presence of an active PCC rule and authorization from the Online Charging System (OCS) for the applicable credit with the specific Charging key. Thus, both conditions are necessary, making Option 4 correct.