The Following Pictures Represent Equal Volumes of Aqueous Solutions of Three

The following pictures represent equal volumes of aqueous solutions of three acids HA (A = X,Y,or Z) ;water molecules have been omitted for clarity.
-Arrange the conjugate bases (A^- = X^-,Y^-,or Z^-) in order of increasing value of K_b.

A) K_b(Z^-) < K_b(Y^-) < K_b(X^-)
B) K_b(Y^-) < K_b(Z^-) < K_b(X^-)
C) K_b(Z^-) < K_b(X^-) < K_b(Y^-)
D) K_b(X^-) < K_b(Z^-) < K_b(Y^-)