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
Retraction of tympanic membrane touching promontory. What is sade's grade? 
Select and explain. 
A. 1, B. 2, C. 3, D. 4
C: 3
Answer: C: 3 
Explanation: Ans. is 'c' i.e., 3 Atelectic grades of pars tensa Sade classification:: Grade 1 = slight retraction of TM over the annulus Grade 2 = the TM touches the long process of the incus Grade 3 = the TM touches the promontory Grade 4 = the TM is adherent to the promontory