Critical infrastructure is defined as which of the following?

The definition of critical infrastructure encompasses the key services and assets that are essential for the security, economy, public health, and safety of a nation. This includes various sectors such as transportation, communication, energy, and water systems, among others. The designation is based on the importance of these services and assets to the operational stability of society as a whole.

The correct choice reflects this broader understanding, emphasizing that critical infrastructure is vital not just for government functions but for the day-to-day lives of citizens and the overall well-being of the nation. Understanding this definition is crucial for professionals in homeland security, as it guides policy and operational priorities when assessing vulnerabilities and potential threats to national safety.