Look at the following program.

$1$ import tkinter

$2$

$3$ def main$()$:

$4$ main$\_$window $=$ tkinter.Tk$()$

$5$ tkinter.mainloop$()$

$6$

$7$ if $\_\_$name$\_\_==\text{'}\_\_$main$\_\_\text{'}$:

$8$ main$()$

What does the code in line $4$ do$?$

It calls a function that runs like an infinite loop.

It creates the GUI's root widget.

It creates an instance of the MainWindow class.

It gets a reference to the operating system's main window.