Redundancy has nothing to do with abuse of high privilege roles. All others can lead to risk of risk of
"abuse of high privilege roles" or "Cloud provider malicious insider"

Network, CPU and Disk(storage) are key subsystems in cloud environment that should be monitored.

All the options given are correct methods of destroying data but when it comes to data in cloud. the most suitable method is cryptographic erasure.
Definition: Cryptographic Erasure
Cryptographic erasure is the process of using encryption software (either built-in or deployed) on the entire data storage device. and erasing the key used to decrypt the data.