What visibility requirement must be met for descending below MDA?

To descend below the Minimum Descent Altitude (MDA) during an approach, the aircraft must be in conditions that meet or exceed the prescribed visibility requirements for that particular approach. This requirement is crucial as it ensures that the pilot has sufficient visual reference to the ground and can navigate safely to the runway environment.

When approaching below MDA, a pilot must have visual references, such as the runway environment or specific landmarks, to ensure that they can maintain a safe descent and landing. The visibility criteria are defined in the approach procedure and take into account factors like the specific terrain, obstructions, and other environmental considerations.

Other options do not adequately capture the critical factors involved in descending below MDA. For instance, while visibility standards can vary, the requirement to meet or exceed the approach-specific criteria is the primary determinant for safely continuing descent during an IFR approach.