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
Gingiva is most commonly affected by deficiency of: 
Select and explain. 
A. Vitamin A, B. Vitamin D, C. Vitamin C, D. Vitamin B
C: Vitamin C
Answer: C: Vitamin C 
Explanation: None