Protein X Can Bind to Either Protein a or Protein

Multiple Choice

Protein X can bind to either protein A or protein B to form a complex.The association constants are 108 M-1 (X with A) and 106 M-1 (X with B) .Which statement is true?

A) In the presence of excess X,it takes fewer molecules of A than B to generate a given amount of complex.
B) The dissociation constant of the complex XA is higher than that of complex XB.
C) B must be a larger protein than A.
D) The values of the association constants indicate that both complexes XA and XB are very unstable in small cells like E.coli.