Explanation
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.

Limits are put in place to enforce a maximum on the amount of memory or processing a cloud customer can use. This can be done either on a virtual machine or as a comprehensive whole for a customer, and is meant to ensure that enormous cloud resources cannot be allocated or consumed by a single host or customer to the detriment of other hosts and customers.

Explanation
A hybrid cloud model spans two more different hosting configurations or cloud providers. This would enable an organization to continue using its current hosting configuration, while adding additional cloud services to enable disaster recovery capabilities. The other cloud deployment models--public, private, and community--would not be applicable for seeking a disaster recovery configuration where cloud services are to be leveraged for that purpose rather than production service hosting.