What defines a "deep-cut" in mining?

The definition of a "deep-cut" in mining typically refers to a mining machine cut that extends beyond a significant depth. In this context, the correct choice indicates that a deep-cut is defined as a mining machine cut extended beyond a depth of 20 feet. This measurement is crucial because it signifies the point at which mining operations often require different safety protocols, equipment, and techniques compared to shallower cuts. Deep cuts can introduce challenges such as increased geological instability, necessitating specific engineering and operational strategies to ensure the safety of personnel and the integrity of the mine.

While other options may reference various aspects of cuts in mining, they do not align with the commonly accepted standards for what constitutes a deep-cut, particularly in terms of depth and the implications for safety and operational procedures.