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
Amino acid carrying ammonia from muscle to liver 
Select and explain. 
A. Alanine, B. Glutamine, C. Arginine, D. Lysine
A: Alanine
Answer: A: Alanine 
Explanation: Under conditions of starvation, the glucose alanine cycle is of special metabolic significance (Fig. 9.30). Alanine is quantitatively the most impoant amino acid taken up by the liver from peripheral tissues, paicularly from skeletal muscle. It forms a major paicipant in inter-organ transpo of nitrogen (Figs 14.4 and 14.5).Ref: DM Vasudevan - Textbook of Biochemistry, 6th edition, page no: 187