Final answer:
IFR low altitude en route charts depict all IR routes and all VR routes that accommodate operations above 5,000 feet AGL.
Step-by-step explanation:
The correct answer is B) 5,000 feet AGL. IFR low altitude en route charts are used by aviators to navigate when flying under Instrument Flight Rules (IFR). These charts depict all IR (Instrument Route) and VR (Visual Route) that accommodate operations above 5,000 feet Above Ground Level (AGL). This is to ensure the safe navigation of aircraft by providing clear routes and altitude information that takes into consideration the air traffic control regulations and separation standards for aircraft.