Task: Class Definition Understanding (ontology: Sciences/Biology)

Which of the following definitions best describes '5beta-dihydrotestosterone'?

A. A C18 steroid with 5beta-configuration formed from nandrolone by reduction across the C4-C5 double bond.
B. A 17beta-hydroxyandrostan-3-one that has beta- configuration at position 5. It is a metabolite of testosterone.
C. A C21-steroid that is 5beta-pregn-11-ene substituted by oxo groups at positions 3 and 20.
D. A 3-oxo-5beta-steroid that is 5beta-pregnan-3-one carrying an additional 20alpha-hydroxy substituent.

Answer: A 17beta-hydroxyandrostan-3-one that has beta- configuration at position 5. It is a metabolite of testosterone.