This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology, Subject name: Biochemistry
All of the following are peptide-based except 
Select and explain. 
A. ACTH, B. GnRH, C. Thyroxin, D. TRH
C: Thyroxin
Answer: C: Thyroxin 
Explanation: Thyroxin is a lipid-soluble hormoneRef: DM Vasudevan, 7th edition, page no: 672