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
Balanced stone is dental stone: 
Select and explain. 
A. Which undergoes rapid expansion, B. In which, accelerators or retarders have been added according to need, C. In which, amount of water of hydration is controlled, D. In which, the crystals are all of uniform size
B: In which, accelerators or retarders have been added according to need
Answer: B: In which, accelerators or retarders have been added according to need 
Explanation: A stone with a setting time established by the addition of proper quantities of both accelerator and retarder is called ‘balanced stone’. 
Typical accelerators are potassium sulfate and potassium sodium tartrate (Rochelle Salts).
Typical retarders are sodium citrate and sodium tetraborate decahydrate (Borax).
Manappalil pg-313