Black steel pipe is usually used for gas lines inside the home. But I can't think of a reason why galvanized steel would cause a problem.
Galvanized pipe is never used for gas lines because the zinc coating flakes off and will clog the filter at the appliance.
********************************************************
--
Answer 2 is incorrect -- Galvanized is permitted in many (all?) jurisdictions, and its use is quite common. In fact, in some jurisdictions, galvanized is actually required where the line is exposed to the weather. I know for a fact that galvanized is permitted in California and Colorado (I'm a General Contractor in both states).
I've been told that some jurisdictions do not permit the use of galavanized for gas lines, but I have yet to see someone cite a building code section and I don't think anyone making this claim was an active contractor. So I consider this anecdotal at best. Bottom line, if in doubt, check with your local AHJ (authority having jurisdiction) -- typically the local city or county building department
********************************************************
Maybe you failed this question on your test.
Answer 2 is correct This is from California plumbing code book.I have a lic in both Ca and AZ and its the same.***response*** you might want to get your glasses checked - your own citation includes galvinized as an approved pipe for gas
***Above-ground gas pipe must be black steel,
galvanized steel, or brass. Copper is not acceptable. Gas pipe
must be at least 6" above the ground unless it's a type approved for burial. Buried gas pipe is not permitted
within any building or structure.
Every appliance is required to have an accessible shutoff valve within 3' of the appliance and ahead of the union
connection to the appliance.
FITTINGS
The couplings or "thread protectors" which are commonly supplied with lengths of pipe are not tapered-thread
type and are not permitted to be used. Ground-joint unions are only allowed at exposed appliance connections
or outside the building on the outlet side of the building shutoff valve. In all other situations where a union-type
connection is required, a left-right nipple and coupling must be used. Bushings are only permitted in exposed
locations and must not be used where they will be covered by permanent construction.
UNDERGROUND GAS PIPE
Underground gas pipe must be factory coated steel pipe, or approved PVC or PE gas pipe.
Factory coated steel pipe is required to be at least 12" below grade. All fittings, short nipples, and nicks in the
factory coating must be wrapped with tape which is listed and marked for that purpose. Such tape is commonly
available in 10 mil and 20 mil thickness, but it must be applied spirally so that the final thickness is at least 40
mils. This type of underground gas pipe has to be separated from the above-ground gas pipe by a dielectric
union or an electrically isolation fitting/ coupling.