2.Which of the following statements about protein-ligand binding is correct? (A) The larger the Ka (association constant), the lower the affinity. (B) The larger the Ka, the faster is the binding. (C) The Ka is equal to the concentration of ligand when half of the binding sites are occupied. (D) The Ka is independent of conditions such as salt concentration and pH. (E) The larger the Ka, the smaller the Kd(dissociation constant).