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
Percent change in water content according to the weight of an agar impression material in various storage media is shown in the following graph. This is least when stored in storage media shown by yellow line on graph. Yellow line represents: 
Select and explain. 
A. Potassium sulfate, B. 100% humidity, C. Water, D. Air
B: 100% humidity
Answer: B: 100% humidity 
Explanation: None