Which of the following best describes a characteristic of underground mining?

Underground mining is characterized by its inherent safety risks mainly due to the confined working conditions and the complexity of the mining environment. Miners operate in underground tunnels where ground stability, ventilation, and exposure to hazardous conditions like gas accumulation or rock falls can present significant dangers. This contrasts with surface mining, where the work is conducted at ground level with generally easier access to safety measures and quicker evacuation routes. The nature of underground mining operations often requires workers to employ rigorous safety protocols and measures to address these heightened risks, making it notably more dangerous compared to surface mining settings.

The other options present different aspects of mining. While surface-level equipment is primarily associated with surface mining operations, underground mining utilizes specialized equipment designed for confined spaces. The claim regarding resource intensity is not entirely accurate, as underground mining can be more resource-intensive, particularly in terms of labor and technology, to ensure safety and operational efficiency. Finally, while underground mining can limit some environmental disturbances compared to surface mining, it can lead to significant impacts such as subsidence and groundwater contamination, depending on the methods and locations utilized. Hence, the characterization of higher safety risks as a defining feature of underground mining is indeed accurate.