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: Pharmacology
Which of the following is not a steroid ? 
Select and explain. 
A. 17α Hydroxyprogesterone, B. Estrone, C. Pregnenolone, D. Relaxin
D: Relaxin
Answer: D: Relaxin 
Explanation: None