Which of the following describes surveillance?

Surveillance is defined as the systematic observation of specified areas or activities. This process involves continually monitoring and gathering information about a target environment or situation, which enables decision-makers to understand developments, identify potential threats, and assess changes over time. Surveillance can utilize various means, including satellite imagery, drone technology, or ground patrols, to ensure accurate and timely intelligence.

The other options do not align with the definition of surveillance. Combat missions focus on direct engagement rather than observation. A passive approach does not generally imply a focus on continuous and systematic observation but rather a lack of direct action that is not characteristic of surveillance. Lastly, using reconnaissance assets in a reserve capacity does not capture the essence of surveillance, which emphasizes ongoing observation rather than reserving resources for potential future use. Thus, the systematic nature of surveillance distinctly sets it apart from other activities related to intelligence operations.