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: Gynaecology & Obstetrics
Gonadotropin levels decline to prepubertal levels by age 
Select and explain. 
A. 6 month to 1 year of age, B. 1 year to 2 years of age, C. 2 years to 3 years of age, D. 3 years to 4 years of age.
B: 1 year to 2 years of age
Answer: B: 1 year to 2 years of age 
Explanation: Gonadotropin levels gradually decline to reach prepubertal levels by age 1 to 2 years.