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: Surgery
Which of the following is true about esophagus except: 
Select and explain. 
A. Serosa not present, B. Middle & lower third made up of striated muscle, C. Lower oesophageal sphincter is a zone of relatively high pressure, D. In achalia cardia LOS tone is increased so that food can not pass below
B: Middle & lower third made up of striated muscle
Answer: B: Middle & lower third made up of striated muscle 
Explanation: Answer-(B) Middle & lower third made up of striated muscleEpithelium is stratified squamous non-keratinized epithelium.Muscularis mucosa contains only longitudinal layer and no circular layer.Mucosa is the toughest and strongest layer.Serosa is absent.Muscularis externa is made up of skeletal muscle fibers only in the upper third, smooth muscles only in the lower third and both types of muscle fibers in middle third. At upper end the longitudinal coat splits into two bundles and the triangular interval between them is called Laimer's tringle which is filled with circular muscle fiber