Question: In a 5G System using Network Exposure Function (NEF) for external exposure with Common API Framework (CAPIF), which of the following is NOT a mandatory support requirement over specific CAPIF reference points?
Option 1: API exposing function over CAPIF-2/2e and CAPIF-3/3e reference points
Option 2: Direct UE: User Equipment to NEF communication without security mechanisms
Option 3: API publishing function over CAPIF-4/4e reference point
Option 4: API management function over CAPIF-5/5e reference point
Explanation: The correct answer is Option 2 because the text explicitly mentions that at least one of the security methods for authentication and authorization, and related security mechanisms must be supported when using CAPIF with an NEF for external exposure. Direct UE to NEF communication without security mechanisms contradicts this requirement, making it the incorrect practice among the options provided. The other options (1, 3, and 4) are all mentioned in the text as mandatory support requirements over specific CAPIF reference points when CAPIF is used with an NEF for external exposure.