Hedges Deck
This one shows metal piping rail on roof deck (uncommon). I cannot find any photos of brass rails on a deck at all (!) but that would be my preference. Brass piping costs about $15/foot for 2" OD. I like your railing choice "A" because the metal is likely to wear better, although have to see a sample of perforated metal because it does not sound very solid and stable.
another example large round window
Q