Which of the following has maximum value of cation/anion radius ratio?

Among the three options KCl, NaCl and MgCl₂ , the size of anion is same. So larger the cation, larger will be the cation/anion ratio i.e., KCI will have-larger cation/anion ratio among the three. So, we left with two options KCI and CaF₂. Among these two CaF₂ will have maximum value of cation/anion ratio because decrease in ionic radii of anion from Cl^- to F^- does not overcome the effect of decrease in ionic radii of cation from K⁺ to Ca²⁺.