In a reaction of the following alkene with HBr, two products are isolated as follows. HBr In an effort to explain the product distribution in this reaction, the following structural rearrangement has been proposed as reactive intermediates. O A "1,2-Hydride shift" What type of structural rearrangement is shown here? O A "1,2-Methyl shift" OA "Keto-enol tautomerism" O Two resonance forms Br O A Carbocation shift Br O A proton shift