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
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: None