Radio Button provides the facility to user to choose one oprtion at a time.To define the RadioButton control together we use the GroupName property.The IsChecked property is used to preselect one option.

<StackPanel>
<RadioButton GroupName="Number" Content="One" IsChecked="True"/>
<RadioButton GroupName="Number" Content="Two" />
<RadioButton GroupName="Number" Content="Three" />
<RadioButton GroupName="Digit" Content="Four" IsChecked="True"/>
<RadioButton GroupName="Digit" Content="Five"/>
<RadioButton GroupName="Digit" Content="Six"/>
</StackPanel>