Q1: In what form does the product of glycolysis enter the TCA cycle?

ANS:A - AcetylCoA

Actually, pyruvate does not enter the citric acid cycle but undergoes some chemical grooming in which a carboxyl group is removed and given off as co2. The 2 carbon compound remaining is oxidised while a molecule of NADH+ is reduced to NA,DH.

Coenzyme adjoins with 2 carbon groups to form acetyl coenzyme An abbreviated as acetyl-CoA so I can say acetyl coA is the best.