This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metabolism of protein and amino acid, Subject name: Biochemistry
Krebs cycle and Urea cycle are linked at 
Select and explain. 
A. Ornithine, B. Fumarate, C. Oxaloacetate, D. Arginine
B: Fumarate
Answer: B: Fumarate 
Explanation: Reference: Harpers illustrated biochemistry 30th edition