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: Pathology
Extreme widening of the periodontal ligament as seen in the radiograph is the characteristic feature of: 
Select and explain. 
A. Scleroderma, B. Paget's disease, C. Pemphigus, D. All of the above
A: Scleroderma
Answer: A: Scleroderma 
Explanation: Extreme widening of the periodontal ligament, two to four times the normal thickness has been reported originally by Stafne and Austin as characteristic of scleroderma.