Explanation: The concept of availability ensures reliable and timely access to data or resources. In other words, availability ensures that the systems are up and running when needed. The availability concept also ensures that the security services are in working order. Answer: A and D are incorrect. The concept of integrity ensures that modifications are not made to data by unauthorized personnel or processes. It also ensures that unauthorized modifications are not made to data by authorized personnel or processes. Answer: B is incorrect. Accountability determines the actions and behaviors of an individual within a system, and identifies that particular individual. Audit trails and logs support accountability.