11. In palladium-catalyzed cross-coupling reactions, such as the Suzuki-Miyaura coupling or Heck reaction, why is the addition of a base typically essential? (A) To increase the oxidation state of the palladium catalyst from Pd(0) to Pd(II) to initiate oxidative addition. (B) To activate the organometallic nucleophile or to neutralize the hydrogen halide (HX) generated during the catalytic cycle. (C) To serve as a sacrificial oxidant that prevents the palladium from precipitating as palladium black. (D) To act as a bulky ligand that occupies coordination sites on the palladium to prevent over-reaction.