Sort the following events to reflect the order in which they occur during vesicle docking onto a target membrane, starting with an inactive Rab in the cytosol. Your answer would be a four-letter string composed of letters A to D only, e.g. DACB. (A) Rab is bound to its effector (tethering protein) on the target membrane. (B) Rab is bound to its Rab-GDI. (C) Rab is bound to the membrane in its GTP-bound form. (D) Rab dissociates from the membrane.