The FIPS 140-2 standard pertains to the certification of cryptographic modules and is not a regulatory framework. The Payment Card Industry Data Security Standard (PCI DSS), the Federal Risk and Authorization Management Program (FedRAMP), and the Health Insurance Portability and Accountability Act (HIPAA) are all regulatory frameworks for sensitive or specialized data.

Object storage is typically used to house virtual machine images because it is independent from other systems and is focused solely on storage. It is also the most appropriate for handling large individual files. Volume storage, because it is allocated to a specific host, would not be appropriate for the storing of virtual images.
Structured and unstructured are storage types specific to PaaS and would not be used for storing items used throughout a cloud environment.