A company uses HUAWEI CLOUD Stack to provide services.

The best verified answer is A. AutoOps built-in scripts . Huawei’s HUAWEI CLOUD Stack O & M documentation states that Automated Jobs automatically detect faults of each cloud service , and that the automation scripts or jobs of each cloud service are displayed and can be centrally managed . That makes AutoOps built-in scripts the most suitable choice for quick diagnosis when VM migration failures happen repeatedly, because this is exactly the kind of recurrent platform-side fault scenario where automated diagnosis scripts are useful.

The other tools are more specialized for different problem domains. CloudNetDebug is described by Huawei as a network diagnosis tool on virtual networks and is mainly used to detect network traffic interruption, packet loss, and full-link virtual network faults. Call chain is associated with application tracing or APM-style request tracing, not VM migration troubleshooting. ECS storage troubleshooting tools are aimed at storage-related fault analysis rather than general VM migration diagnosis.

Therefore, for fast diagnosis of frequent VM migration failures in Huawei Cloud Stack O & M, the most appropriate tool is AutoOps built-in scripts , so the verified answer is A .

========