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: ENT
What is true in case of perforation of pars flaccida - 
Select and explain. 
A. CSOM is a rare cause, B. Associated with cholesteatoma, C. Usually due to trauma, D. All of the above
B: Associated with cholesteatoma
Answer: B: Associated with cholesteatoma 
Explanation: Tympanic membrane can be divided in 2 parts:
Parstensa : It forms most of the tympanic membrane. Its periphery is thickened to form fibro cartilaginous ring called as annulus tympanicus.
Pars Falccida : It is situated above the lateral process of malleus between the notch of Rivinus and the anterior and posterior malleolar fold.
Ref. Dhingra 6/e p59, 5/e p 78