This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: TCA Cycle, Subject name: Biochemistry
Which molecule is regarded as carrier of TCA cycle ? 
Select and explain. 
A. Acetyl CoA, B. Oxaloacetate, C. Citrate, D. ATP
B: Oxaloacetate
Answer: B: Oxaloacetate 
Explanation: Oxaloacetate is regarded as: Carrier of TCA cycle 1st substrate of TCA catalytic role in TCA Acetyl CoA is not glucogenic; not carrier, 1st substrate or intermediate of TCA cycle