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The compound shown is an ortho-substituted benzoic acid. It is a stronger acid than benzoic acid mainly because

  1. Athe ortho group forces COOH out of the ring plane, an ortho effect
  2. BCH3 forms an intramolecular hydrogen bond with COOH
  3. CCH3 is a strong electron-withdrawing group
  4. DCH3 increases resonance between the ring and COOH

Answer: A

The compound is o-toluic acid (pKa 3.91 vs 4.20). The ortho substituent crowds the COOH group and twists it out of the plane of the ring, which removes conjugation of the ring with the carboxyl group and stabilises the carboxylate (the ortho effect).
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