Answer:
C. Draw a circle around a diameter.
Explanation:
The first step when inscribing a square, equilateral triangle, or hexagon in a circle - Draw a circle around a diameter.
Depending on various constructions, Step 2 here will be - Draw an arc that intersects the circle at two points.
Next will be - Connect the endpoints of the diameters to form a square or Connect all six points on the circle.