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
In starvation, nitrogen is carried from muscle to liver and kidney by 
Select and explain. 
A. Alanine, B. Aspartic acid and Serine, C. Glycine, D. Asparagines
A: Alanine
Answer: A: Alanine 
Explanation: Transport of alanine from muscle to liver (glucose-alanine cycle) has two functions :-

Providing substrate for gluconeogenesis
Transport of ammonia (NH4+) to liver for urea synthesis