Answer
The command will draw a square with diagonal of 100.
Work Step by Step
turtle.circle draws a circle with given radius. The center is radius units left of the turtle.
As the circle is approximated by an inscribed regular polygon, steps determines the number of steps to use. If not given, it will be calculated automatically. Since step=4 here, a square will be draw of diagonal 100 (since diagonal= 2*radius value provided)
