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 first radiographic sign of chronic pulpal infection of primary molars is: 
Select and explain. 
A. Periapical bony changes, B. Root resorption, C. Changes in bony furcation area, D. Widening of apical periodontal ligament
C: Changes in bony furcation area
Answer: C: Changes in bony furcation area 
Explanation: None