Piping installed by tunneling shall be protected from _____.

The correct answer focuses on the necessity of protecting piping installed by tunneling from uneven loading. In a tunneling environment, the structural integrity of the soil and surrounding materials can be unpredictable due to the excavation process, which can result in varying levels of pressure and support around the pipe. Uneven loading can lead to significant stress on the piping, potentially causing deformation, leaks, or failure of the system.

By ensuring that the piping is protected from these uneven loads, it enhances the overall reliability and safety of the plumbing system. Proper installation techniques and support mechanisms help mitigate the risks associated with changes in load distribution that are common in tunneling conditions.