What do tips #3 and #4 have in common?

Hi! your answer would be  the women's association.  here's why:   "the childrens toys" should be "the children's toys".  there's no apostrophe anywhere, and should go after "children". it does  not go after the 's' because children is already plural, and you usually only add an apostrophe after a plural noun ends with an s, like boys or girls, for example. that is the boys' toys."the women's association", is correct.  it's kinda like the one above.  "the childrens' toys", is not correct. reason why is explained in the first one.  "none of these" isn't correct, because "the women's association" is correct.  hoped i and if you have any more questions, ask me.  -dawn