18.下列程序绘制的图形是？（　） import turtle screen = turtle.Screen() pen = turtle.Turtle() pen.forward(100) pen.

18.下列程序绘制的图形是?(　)

importturtle

screen=turtle.Screen()

pen=turtle.Turtle()

pen.forward(100)

pen.right(90)

pen.forward(100)

pen.right(90)

pen.forward(100)

pen.right(90)

pen.forward(100)

turtle.done()

A.长方形

B.三角形

C.正方形

D.圆形