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
What is the function of humectants in dentrifrices: 
Select and explain. 
A. Liquefies the dentrifrice, B. Prevents water loss and hardening on exposure to air, C. Flavors the tooth paste, D. Cleans tooth surface effectively
B: Prevents water loss and hardening on exposure to air
Answer: B: Prevents water loss and hardening on exposure to air 
Explanation: None