Question: What are the charging-related functionalities that the Common API Framework (CAPIF) MUST support for service APIs usage, according to 3GPP standards?
Option 1: Online and offline charging, with mechanisms for recording invocation count, timestamp, and API location on a per invoker basis.
Option 2: Only online charging, with limited recording capabilities for API usage (e.g., no timestamp).
Option 3: Offline charging solely, requiring manual logging of API invocations without per invoker basis tracking.
Option 4: No direct charging support; relying on external systems for all billing and usage tracking.
Explanation: The correct answer reflects the comprehensive approach to charging support as mandated by the standards. This includes both online and offline charging capabilities, coupled with detailed recording mechanisms (invocation count, timestamp, and API location) to facilitate accurate billing on a per API invoker basis, aligning with the requirements outlined for CAPIF in the context of 3GPP Northbound APIs.