Sometimes, it's really hard, with the bad quality BRs hatcheries are putting out today. Their barring is atrocious in some cases and I suspect they are actually crosses in others. Even my hatchery hens were much better looking than many I've seen of late that were supposedly straight from some...
Yours appears to have yellow legs, just very pale yellowish with a dark wash down the fronts, which usually makes them appear more greenish than yellow.
I was hoping you'd say the comb wasn't really all that pink, that it was just the camera or the way the picture took or something, but...
I almost think you may have a sex link cockerel from the bright pink comb at that very young age, which would have looked just like a BR pullet. I hope I'm wrong, but I've never seen a super bright pink comb and wattles on a less than 5 week old BR pullet, and there have been hundreds hatched...
Is that comb really that bright pink? If it is, I doubt pullet. More likely a crossbreed cockerel, but pictures can be deceiving.
A 12 week old BR pullet doesn't have as much color in the comb as that chick does. BR cross cockerels will be dark like pure BR pullets, even with dark on the legs...