Which of the compounds shown below is much more acidic than the others? Provide a brief explanation for your answer.

• A. Compound A.
  Compound A is an aromatic compound. Therefore, it will lose a proton readily to maintain its aromatic character.
• B. Compound B.
  An aromatic anion is formed when compound B loses a proton. Therefore, compound B will lose a proton most easily.
• C. Compound C.
  A resonance stabilized anion is formed when compound C loses a proton. Therefore, compound C will lose a proton most easily.
• D. Compound D.
  An extended conjugation system is formed when compound D loses a proton. Therefore, compound D will lose a proton spontaneously.

Answer: (B)