Biology · Respiration in Plants

In the initial reaction of the Tricarboxylic Acid (TCA) cycle, what is the nature of the condensation reaction and the carbon counts of the primary substrates involved?

1. A
   A 2-carbon acetyl group of acetyl CoA condenses with 4-carbon oxaloacetic acid (OAA) and water, catalyzed by citrate synthase to yield 6-carbon citric acid.
2. B
   A 2-carbon acetyl group condenses with 5-carbon \( \alpha \)-ketoglutarate to form 7-carbon intermediate.
3. C
   A 4-carbon succinate condenses with 2-carbon glyoxylate to regenerate oxaloacetic acid.
4. D
   A 3-carbon pyruvate condenses with a 3-carbon triose phosphate to form a 6-carbon sugar.