What aligns with the focus of intrusion systems regarding evidence of threats?

The focus of intrusion detection systems is primarily centered around real-time monitoring, which is crucial for identifying and responding to potential threats as they occur. This aspect allows organizations to detect unauthorized access or abnormal behavior in their networks or systems immediately. Real-time monitoring facilitates the collection and analysis of data that can provide immediate alerts, thus enabling swift incident response.

In contrast, while user training, cost efficiency, and environmental safety are all important aspects of organizational security and management, they do not directly pertain to the core function of an intrusion detection system. User training aids in preventing human error, cost efficiency relates to budget considerations, and environmental safety concerns the physical or ecological aspects of systems, none of which are the primary focus of monitoring and responding to security threats in a real-time context.