Which statement defines Availability?

• A. Ensuring systems and data are accessible when needed.
• B. Preventing a sender from denying an action.
• C. Verifying the identity of a user or system.
• D. Granting permissions after authentication.

Answer: (A)

Availability means systems and data are accessible when needed, focusing on uptime, reliable access, and resilience against failures or attacks. To keep services reachable, teams use redundancy, failover, regular backups, multiple network paths, and solid incident response so authorized users can reach resources promptly even during problems.

The other statements describe different security properties: preventing a sender from denying an action is non-repudiation, verifying identity is authentication, and granting permissions after authentication is authorization.