Which one of the following enzymes provides a link between glycolysis and the citric acid cycle?
PDH complex consist of 3 Enzymes and 5 Coenzymes
Three enzymes are:

Pyruvate Dehydrogenase bound to Thiamin Diphosphate
Dihydrolipoyl Transacetylase, the prosthetic group is oxidised Lipomide
Dihydrolipoyl  Dehydrogenase, contains FAD.

Coenzymes (very important)

Thiamine Diphosphate (TDP)
Lipomide
Coenzyme A
FAD
NAD

Key Concept:
 Pyruvate Dehydrogenase  which converts pyruvate to acetyl CoA provides a connecting link between glycolysis and citric acid cycle.
Lactate dehydrogenase
Pyruvate Kinase
Citrate synthase
Pyruvate dehydrogenase