This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology and Reproduction, Subject name: Physiology
Common precursor of mineralocorticoid, glucocorticoids and sex steroids: 
Select and explain. 
A. Pregnenolone, B. a- hydroxyprogesterone, C. Dehydrotesterone, D. Deoxycorticoid
A: Pregnenolone
Answer: A: Pregnenolone 
Explanation: Ans. (a) Pregnenolone(Ref: Ganong, 25th ed/p.362)Adrenal steroid hormones are derived from cholesterolIn the mitochondria, cholesterol is converted to pregnenolone by cholesterol desmolase, also called as side- chain cleavage enzyme