An optically active alkyne A (C₁₀H₁₄) can be catalytically hydrogenated to butylcyclohexane. Treatment of A with EtMgBr liberates no gas. Catalytic hydrogenation of A over Pd/C in the presence of quinoline poison and treatment of the product with O₃ and then H₂O₂ gives an optically active tricarboxylic acid C₈H₁₂O₆. (A tricarboxylic acid is a compound with three —CO₂H groups.) Give the structure of A, and account for all observations.