What indicates that Addison Airport is in Class D airspace?

Addison Airport being in Class D airspace is accurately indicated by the segmented blue circle marking on aeronautical charts. This type of symbol represents the lateral boundaries of Class D airspace, which is typically established around airports with an operational control tower. Class D airspace extends vertically from the surface to typically 2,500 feet above the airport elevation.

The segmented blue circle specifically denotes that pilots must communicate with the control tower when operating within this airspace, which is a fundamental characteristic of Class D airspace. Understanding this visualization helps pilots recognize the airspace type and its associated requirements for communication and navigation.

The other options, while they denote different aspects of airspace classifications, do not specifically indicate Class D airspace. Solid magenta lines represent Class C airspace, compass rose markings indicate a fixed reference for navigation, and dashed magenta circles suggest that the surrounding airspace is uncontrolled or not requiring ATC communication, which is not pertinent to Class D airspace.