A display that shows an aircraft's altitude, attitude, and airspeed is commonly referred to as which of the following?

The correct answer is the Primary Flight Display. This display is specifically designed to present essential flight information to the pilot, which includes altitude, attitude, and airspeed. It consolidates critical data required for safe and effective flight management, allowing pilots to quickly assess their aircraft's performance and orientation.

In contrast, while a Navigation Display focuses primarily on providing navigational information such as waypoints and routes, and a Multi-Function Display may show various other types of data including weather or engine information, neither of these serves the same fundamental primary flight functions as the Primary Flight Display. The Electronic Flight Instrument System refers to the entire system of electronic displays and components used in modern aircraft, which may include multiple types of displays, but does not specifically identify the display dedicated to primary flight information. Thus, the Primary Flight Display is uniquely suited to fulfilling the need for real-time flight parameter monitoring.