how to know which checkbox or radiobutton has clicked

//source codehow to know which checkbox or radiobutton has clicked
//try to crate the sme form as shon in fig.

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace WindowsProject
{
public partial class Form5 : Form
{
public Form5()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
if (radioButton1.Checked)
MessageBox.Show("Radio Button1 is selected");
else if (radioButton2.Checked)
MessageBox.Show("Radio Button2 is selected");
else if (radioButton3.Checked)
MessageBox.Show("Radio Button3 is selected");
}
private void button2_Click(object sender, EventArgs e)
{
if (checkBox1.Checked)
MessageBox.Show("Check Box1 is selected");
if (checkBox2.Checked)
MessageBox.Show("Check Box2 is selected");
if (checkBox3.Checked)
MessageBox.Show("Check Box3 is selected");
}
private void checkBox1_CheckedChanged(object sender, EventArgs e)
{
if (checkBox1.Checked)
MessageBox.Show("Selected");
else
MessageBox.Show("De-Selected");
}
}
}