What are the red inset lights installed along the runway holding position markings called?

The correct term for the red inset lights installed along the runway holding position markings is "runway stop bars." These lights serve an important safety function by indicating to pilots when they must stop their aircraft at a runway holding position. The red lights provide a clear visual cue, especially in conditions of low visibility, ensuring that aircraft do not inadvertently enter an active runway.

Runway stop bars are usually installed at the threshold of runways, and their illumination signifies that it is unsafe to cross the holding position, thereby preventing runway incursions. This system is a critical component of airport safety protocols, designed to facilitate safe operations on the airfield.

The other options represent different types of airfield lighting that serve various purposes. Taxiway lights provide guidance along taxiways, approach lights assist pilots in landing by indicating the approach path, and landing lights are typically associated with the aircraft itself for visibility during landing and takeoff maneuvers. Each of these lighting systems plays a unique role in airport operations but does not serve the specific function of marking runway holding positions.