This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Ear, Subject name: ENT
What is the length of external auditory canal? 
Select and explain. 
A. 2.5 cm, B. 1.5 cm, C. 1cm, D. 2 cm
A: 2.5 cm
Answer: A: 2.5 cm 
Explanation: Ans. (a) 2.5 cmRefi Dhingra's ENT 5th ed. / 4* Length of external auditory canal- 24 mm (2.4cm)* Shape: S- shaped* Outer 1/3rd cartilaginous part (8mm)* Inner 2/3rd: Bony part (16mm)