What type of aircraft operation is NOT allowed under VFR flight rules?

Answer: C — Flying in IMC (Instrument Meteorological Conditions)

The reasoning behind the answer lies in the definition and requirements of Visual Flight Rules (VFR). VFR is designed for pilots who fly primarily by visual reference to the ground and other landmarks, rather than relying on instruments. Under VFR, pilots must maintain specific visibility and distance from clouds to ensure safe navigation and avoid colliding with terrain or other aircraft. Flying in Instrument Meteorological Conditions (IMC) involves flying in weather conditions where visibility is poor, and pilots cannot rely on visual cues; they must use cockpit instruments to fly safely. This type of operation is contrary to the principles of VFR, as it requires adherence to Instrument Flight Rules (IFR), which are designed for flights conducted solely by reference to instruments during poor visibility. In contrast, flying in uncontrolled airspace, within military restricted zones, or at night can all be conducted under VFR, provided the pilot meets the necessary requirements such as visibility criteria and operational limits. Thus, IMC operations distinctly fall out of the capability of VFR, making this answer the correct choice.