Your answer is incorrect because it is 60psi, not 60 inches
From the course:
Natural gas runs from the main into a home or business in what’s called a service line. Today, this line is likely to be a small-diameter plastic line an inch or less in diameter, with gas flowing at a pressure range of over 60 psi to as low as ¼ psi (about 7″ wc).
Of the answer choices we give you, one is correct, but it requires you to do a conversion from psi to inches wc. We showed you in the previous unit what the conversion factor is for that. Does that make sense?