python tkinter -如何设置单选按钮菜单的初始选择？

import tkinter as tk

# 创建主窗口
root = tk.Tk()

# 创建一个IntVar变量来跟踪单选按钮的选择
selected_option = tk.IntVar()

# 设置初始选择为第二个单选按钮（值为1）
selected_option.set(1)

# 创建三个单选按钮
option1 = tk.Radiobutton(root, text="Option 1", variable=selected_option, value=0)
option2 = tk.Radiobutton(root, text="Option 2", variable=selected_option, value=1)
option3 = tk.Radiobutton(root, text="Option 3", variable=selected_option, value=2)

# 将单选按钮放置在窗口上
option1.pack()
option2.pack()
option3.pack()

# 运行主循环
root.mainloop()

selected_option = tk.StringVar()
selected_option.set("Option 2")