Which of the following compounds is most reactive towards the E1cB elimination reaction?

Step-by-step solution

The E1cB elimination reaction proceeds via a two-step mechanism involving the formation of a carbanion intermediate. The rate of the reaction is determined by the stability of this carbanion, which is formed by the abstraction of a -proton by a base. In option (A), abstraction of the proton from the sp^3 carbon of the cyclopentadiene ring generates a cyclopentadienyl anion. This intermediate is planar, fully conjugated, and possesses 6 electrons, making it aromatic and highly stable. In option (B), abstraction of t