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
Caries activity is increased in 
Select and explain. 
A. Xerostomia, B. Sugar diet, C. Taking much carbohydrate food, D. None
A: Xerostomia
Answer: A: Xerostomia 
Explanation: None