Correct Answer: C
According to the CISSP Official (ISC)2 Practice Tests3, reciprocal backup site agreements are considered to be easy to implement for similar types of organizations. A backup site is a location or a facility that is used to restore the business operations and functions, as well as the supporting resources, such as data, systems, personnel, and facilities, in the event of a disaster that disrupts the normal operations of an organization. A backup site can be classified into different types or levels, based on the availability, functionality, and compatibility of the backup site, such as the hot site, the warm site, or the cold site. A reciprocal backup site agreement is a type of backup site agreement that is established between two or more organizations that have similar types or levels of backup sites, and that agree to provide or share their backup sites with each other in the event of a disaster that affects one or more of the organizations. A reciprocal backup site agreement is considered to be easy to implement for similar types of organizations, as it does not require a lot of resources, costs, or efforts to set up or maintain the backup site agreement, and as it provides a high level of compatibility and flexibility for the backup site agreement.