It is very likely that all the girls will want pink - so I have bought enough pink ones for every single girl to have one if she wants.
Of course, some of the girls may not want pink. That's fine - they can choose from the other colours.
But if some of the girls choose colours other than pink, some boys may end up with pink - unthinkable! Pink is anathema to most boys: it's a 'girl's colour'.
So I have also had to make sure that there are enough folders for every single child - both boys and girls - to have a non-pink one.
My usual way to avoid all this drama - e.g. when providing card for crafts - is to not provide pink (and sometimes purple) at all. If there is no pink the girls will happily chose all kinds of colours - it's only when pink is available that their 'you-are-a-girl-therefore-you-must-have-pink' indoctrination kicks in.
Once you know the kids well, of course, you will know if there are girls who prefer other colours. And one boy I had would choose pink if there was no red, as it was the closest colour to red (he's grown out of such heretical thoughts now of course).
But before you know the children, it's as well to be aware that offering pink may cause a problem. Pink is annoying.
Update: All the girls chose pink. And one of the boys asked, "Why do girls like pink so much?"