Where can plastic (polyethylene) gas piping be installed?

The correct choice specifies that plastic (polyethylene) gas piping can be installed outdoors underground, within buildings, and under slabs. This flexibility in installation locations is crucial because polyethylene is designed to be durable and resistant to external factors such as moisture and corrosion.

When installed underground, polyethylene piping benefits from protection against UV light and physical damage. Under slabs, it can help ensure that the gas supply is safe and efficient without compromising the structural integrity of the building. Furthermore, its use within buildings is permitted, as it complies with safety codes when properly installed and supported.

The other choices are limited in scope, focusing either solely on residential applications or specific locations, which do not reflect the breadth of where polyethylene gas piping can be effectively and safely utilized.