Correct Answer: C
Although elements of all of the systems described could require specific controls for confidentiality, given the descriptions above, system b fits the definition most closely of a system requiring a very high level of confidentiality. Answer a is an example of a system requiring high availability. Answer c is an example of a system that requires medium integrity controls. Answer d is a system that requires only a low level of confidentiality. Asystem may need protection for one or more of the following reasons: Confidentiality. The system contains information that requires protection from unauthorized disclosure. Integrity. The system contains information that must be protected from unauthorized, unanticipated, or unintentional modification. Availability. The system contains information or provides services which must be available on a timely basis to meet mission requirements or to avoid substantial losses. Source: NIST Special Publication 800-18, Guide for Developing Security Plans for Information Technology Systems