This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Systemic histology, Subject name: Anatomy
which is the strongest layer of oesophagus? 
Select and explain. 
A. mucosa, B. sub mucosa, C. muscularis propria, D. adventitia
B: sub mucosa
Answer: B: sub mucosa 
Explanation: sub mucousa is strongest layer of oesophagus and should be included in sutures