What are the two types of National Terrorism Advisory Alerts?

The correct choice is based on the established framework of the National Terrorism Advisory System. The two types of National Terrorism Advisory Alerts are "Elevated" and "Imminent."

An Elevated alert indicates there is a credible threat of terrorism, signaling that heightened vigilance and awareness are necessary. This alert informs the public and authorities that there may be specific threats that could lead to potential attacks, prompting preparedness and preventive measures.

On the other hand, an Imminent alert is used when there is a credible, specific, and ongoing threat of an attack. This urgency communicates an immediate need for action to protect potential targets, as a terrorist act could occur at any moment.

Understanding the distinctions between these alerts is crucial for responding effectively to terrorist threats and ensuring public safety. The other options do not align with the official terminology and categories of alerts defined by the National Terrorism Advisory System.