This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Sexuality and intersexuality, Subject name: Gynaecology & Obstetrics
A 9-year-old girl presents with menarche. History reveals thelarche at the age of 7 years and adrenarche at the age of 8 years- the M/C cause of this condition in girls is: 
Select and explain. 
A. Idiopathic, B. Gonadal tumor, C. Mc cure albright syndrome, D. Hypothyroidism
A: Idiopathic
Answer: A: Idiopathic 
Explanation: Precocious pubey It is the appearance of appropriate secondary sexual charecters before the age of 8 years and occurance of menstruation before the age of 10 years The most common cause is constitutional(idiopathic -75% cases) due to premature activation of HPO Axis. SHAW&;S TEXTBOOK OF GYNAECOOGY,Pg no:56,15th edition