Final answer:
None of the listed product options are correct for the Wittig reaction of benzyltriphenylphosphonium chloride with cinnamaldehyde and potassium phosphate. The actual product would be an alkene, often referred to as 'stilbene', specifically the trans or (E)-isomer.
Step-by-step explanation:
When benzyltriphenylphosphonium chloride reacts with cinnamaldehyde and potassium phosphate, it undergoes a reaction known as the Wittig reaction, which is used to create alkenes from phosphonium ylides and carbonyl compounds. In this case, the ylide formed from benzyltriphenylphosphonium chloride reacts with the aldehyde group in cinnamaldehyde to form an alkene as the major product. Since the potassium phosphate is acting as a base in this reaction, its role is to deprotonate the phosphonium salt to form the ylide. It does not form part of the final organic product but is instead a part of the reaction's by-products. Therefore, among the options provided, none represent the correct product of this reaction because all options unrealistically include parts of the reactants or the potassium from the base in the final organic product name. The accurate product would simply be the corresponding alkene, commonly called 'stilbene' if it is a trans-isomer or '(E)-stilbene' to specify its geometry.