Correct Answer: ATo achieve a comprehensive backup including the configurations of the chassis, FEX, rack servers, IOMs, and blade server, and to ensure it can be properly restored, the best approach is to perform an all configuration backup. This method captures the full set of configurations needed for the system restore process, ensuring that all relevant elements are backed up and can be restored accurately. An all configuration backup provides a complete snapshot, which is crucial for effective system restoration, making it the most comprehensive and suitable choice for the engineer's needs.