This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: G.I.T, Subject name: Surgery
Early stage of carcinoma esophagus is diagnosed by 
Select and explain. 
A. Barium meal, B. Trans oesophageal USG, C. MRI, D. Fluoroscopy
A: Barium meal
Answer: A: Barium meal 
Explanation: .investigations for carcinoma oesophagus includes 1)barium swallow -shouldering sign and irregular filling defect.RAT TAIL defect in fluoroscopy is typical. 2)oesophagoscopy -to know lesion, extent and types. 3)biopsy -histological evaluation 4)X-ray /CT/MRI/ bronchoscopy/chromoendoscopy/oesophageal endosonography ref: SRB&;s manual of surgery,5th ed, pg no 806