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: Dental
Instrumentation well short of the apical foramen can result in: 
Select and explain. 
A. Forcing necrotic material into the periapical region, B. Shelling or ledging the canal, C. Traumatizing the periapical tissues, D. Grossly enlarging the apical foramen
B: Shelling or ledging the canal
Answer: B: Shelling or ledging the canal 
Explanation: None