At what altitude can VFR operations typically be conducted?

VFR (Visual Flight Rules) operations are primarily defined by the need for visual reference to the ground and the ability to navigate and avoid obstacles and other traffic. Flying VFR typically requires pilots to operate below cloud cover, as this ensures good visibility and the ability to maintain visual contact with the terrain and other aircraft.

The choice that states "Below the cloud cover, depending on visibility" accurately reflects the fundamental requirement for VFR flight. Pilots must ensure that they can see and avoid obstructions, which includes having a clear view of the clouds and the ground. The specific altitude at which this can occur is highly variable and depends on factors such as local regulations, weather conditions, and the pilot's ability to maintain that visual reference.

In contrast, the other choices may not encapsulate the full scope of VFR requirements. For example, operating below 10,000 feet AGL or under 18,000 feet MSL is too restrictive and doesn't account for the importance of visibility and cloud clearance in VFR operations. This means while there could be operational rules regarding altitude, what fundamentally governs VFR flight is visibility and cloud cover, making option C the most accurate choice for typical VFR conditions.