Question: What is the default implied value of the Usage-Monitoring-Level AVP if it is not provided by the Policy and Charging Rules Function (PCRF) in a Diameter message?
Option 1: SESSION_LEVEL (0) - Entire IP-CAN session
Option 2: PCC_RULE_LEVEL (1) - One or more PCC rules (applicable to Gx reference point)
Option 3: ADC_RULE_LEVEL (2) - One or more ADC rules (applicable to Sd reference point)
Option 4: No Default Value - Explicit provision is always required
Explanation: This value indicates a default application scope when the Usage-Monitoring-Level AVP is omitted.