A Natural Gas Service Regulator is normally set to deliver pressure from:

A natural gas service regulator is designed to reduce the pressure of natural gas from the supply line to a usable level for residential or commercial appliances. It typically operates to deliver pressure measured in inches of water column (W.C.), which is a standard measurement for low-pressure gas systems.

The correct answer indicates that a service regulator is set to deliver pressure from pounds to 7 inches W.C. This reflects the way natural gas systems function, where the incoming gas supply might be at a high pressure (expressed in pounds per square inch, PSI), but the usable pressure required for most appliances is significantly lower, often measured in inches of water column.

The other answer choices either refer to inappropriate pressure ranges or incorrect units for the application of natural gas service regulators, making them unsuitable. Understanding the correct operating pressure is crucial for safety and efficiency in gas systems.