What distinguishes primary radar from secondary radar in air traffic control?

Answer: B — Primary radar detects objects through the reflection of radio waves

The characteristic that distinguishes primary radar from secondary radar lies in how each system operates to detect and track aircraft. Primary radar functions by emitting radio waves that travel through the atmosphere. When these radio waves encounter an object, such as an aircraft, they are reflected back to the radar receiver. This reflection allows the radar system to determine the presence and location of the aircraft. Thus, primary radar is effective for detecting any object, regardless of whether it has a transponder. In contrast, secondary radar systems utilize a different method. They depend on active transponders onboard aircraft to respond to interrogation signals from the radar. This response allows for more detailed information about the aircraft, such as its identity and altitude. Other options highlight concepts that do not accurately describe the fundamental differences between primary and secondary radar. For instance, secondary radar does not provide navigational assistance specifically for VFR (Visual Flight Rules) aircraft; its primary function is to enhance identification and tracking capabilities of aircraft equipped with transponders.