Any one of A, B, C could be the answer

Say the box contain White ball lebel as WR

" " Red " " " W

" " WhiteRed " " " R

If u put up a ball from box lebel R and the color of ball also Red

Then it must not be box of Red ball (As all boxes are mislabeled)

------->The box is filled up with WhiteRed

Next we have 2 boxes, and one box lebel White

---------> This box is filled up with Red balls (As it is also mislebeled and We already marked up WhiteRed Box)

----------> Last box must be filled up with White balls

Similarly in other approach too we get the correct result