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
Oral prophylaxis is contraindicated in: 
Select and explain. 
A. Prepubertal gingivitis, B. Pregnancy gingivitis, C. Ulcerative refractory gingivitis, D. Leukemic gingivitis
D: Leukemic gingivitis
Answer: D: Leukemic gingivitis 
Explanation: None