This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrine System, Subject name: Physiology
Which of the following hormone is not a protein derivative? 
Select and explain. 
A. Growth hormone, B. Insulin, C. Glucagon, D. Thyroxine
D: Thyroxine
Answer: D: Thyroxine 
Explanation: PROTEIN DERIVATIVES STEROID DERIVATIVES TYROSINE DERIVATIVES GROWTH HORMONE COISOL THYROID HORMONES INSULIN ALDOSTERONE CATECHOLAMINES GLUCAGON SEX STEROIDS