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
Mgo added to alginate power to modify which property: 
Select and explain. 
A. Increases surface character., B. Increases shelf life., C. Increases shear and tear strength., D. Improve strength.
A: Increases surface character.
Answer: A: Increases surface character. 
Explanation: MgO added in alginate powder leads to improve its surface character mainly as well as it increased tensile strength, hardness of model, elastic modulus & Improved thermal stability.