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
All the following are peptide based except ? 
Select and explain. 
A. ACTH, B. GnRH, C. Thyroxin, D. TRH
C: Thyroxin
Answer: C: Thyroxin 
Explanation: Ans. is 'c' i.e., Thyroxin