This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
What supplies ammonia to liver ? 
Select and explain. 
A. Arginine, B. Alanine, C. Lactate, D. Pyruvate
B: Alanine
Answer: B: Alanine 
Explanation: Ans. is 'b' i.e., Alanine Transpo of alanine from muscle to liver (glucose-alanine cycle) has two functions :?Providing substrate for gluconeogenesisTranspo of ammonia (NH4+) to liver for urea synthesis.