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: Radiology
Which is the investigation of choice in a case of stricture esophagus caused by corrosive poisoning ? 
Select and explain. 
A. Endoscopy, B. Barium meal, C. Pharyngoscopy, D. X rays
A: Endoscopy
Answer: A: Endoscopy 
Explanation: The corrosive injury is more common in females. Most of the patients were of younger ages. Acid ingestion was more common than alkali ingestion, and most had suicidal intentions. Early upper G.I. endoscopy has a definite role in diagnosing the severity of the injury and in planning the management. The best time to assess the injury is by 12-48 hours of ingestion of the corrosive substances. Most of the patients with corrosive injuries can be managed conservatively with follow up for the stricture, which is the most common complication that is often treated by dilatation.