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
Setting time of alginate is best regulated by the: 
Select and explain. 
A. Amount of retarder added during the manufacturing process, B. Changing the temperature of mixing water, C. Modification in the W/P ratio, D. Speed of mixing or mixing time
A: Amount of retarder added during the manufacturing process
Answer: A: Amount of retarder added during the manufacturing process 
Explanation: Though setting time of alginate can be changed or regulated by any of the above method, but most of them leads to changes or aﬀect the properties of ﬁnal set alginate. Only available best method to regulate it is by a speciﬁc amount of retarder added during the manufacturing process.
Also know

Setting time of Fast-setting alginate = 1.5 to 3 min
Setting time of Normal-setting alginate = 3 to 4.5 min