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
The most important diagnostic test to differentiate between an Acute periapical Abscess and a Phoenix Abscess is 
Select and explain. 
A. Pulp testing, B. Radiographs, C. History, D. Percussion
B: Radiographs
Answer: B: Radiographs 
Explanation: None