Based on the information given, the thing constructed first when creating the circle is B. perpendicular bisectors of the sides of the triangle.
From the information given, in a triangle, there are some properties inherent such as the perpendicular bisectors of all sides being concurrent.
Also, it aligns at a point called the circumcentre of the triangle. When we draw the perpendicular bisector for a side AB, we get that all points on the perpendicular bisector are equidistance from A and B.
Therefore, the thing constructed first when creating the circle is the perpendicular bisectors of the sides of the triangle.
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