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
Pregnenolone is not in the biosynthetic pathway of which substance? 
Select and explain. 
A. Coisol, B. Estrogen, C. DHEA, D. 1,25(OH)2D
D: 1,25(OH)2D
Answer: D: 1,25(OH)2D 
Explanation: All the steroids listed include pregnenolone early in their biosynthetic pathway. 1,25(OH)2D is derived from vitamin D and does not include pregnenolone in its biosynthetic pathway.