Yep - fourth sock. And I reckon I'll have enough yarn left from this 100g ball for another pair of junior socks after this one too!
This is the bigger size for my eldest DD - adult UK shoe size 3.
I had to rip it out just after the heel and lengthen the foot - it measured right but wasn't quite long enough when tried on.
You'd think I'd learn about ribbing pulling a measurement out by now wouldn't you?!