X bars are chrome from the factory, same as C.
D+ bars are black painted although they are a similar (same?) shape.
Not 100% sure if A bars are the same as C/X or not.
Also beware the supersceded part numbers. You can probably still order "YZ125X handlebars" from Yamaha, but you'll almost certainly get the D/E type (or worse). There's also something that Scott W told me about the crossbrace diameter on the replacement bars (its not right).
I have a pair of chrome ones here (pretty sure they were originally on an A model), but they will need rechroming. They're one of those things where I think "Can't let them go", but on the other hand, I'd greatly prefer alloy bars on a ride/race bike. If you can handle the need to rechrome, then I'll get some pics.