I don't see anything at this point that screams roo honestly on any of them...but wait a few weeks and who ever is a roo, the combs will start to get red very soon. Good luck!
That is VERY true...it's always a guess until they're older and it's obvious. I had some that I was POSITIVE were roos..bout the same age as yours..nope..pullets, lol. Its like their combs disappeared as they got older.
First one, if you look at it enough...looks pullet-ish too...I think it's the stance with the more noticeable comb that makes you immediately think roo.