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
Scleroderma involves: 
Select and explain. 
A. Tightening of oraL mucosa and periodontal involvement, B. Multiple palmar keratosis, C. Raynaud's phenomenon, D. All of the above
D: All of the above
Answer: D: All of the above 
Explanation: None