Knockout MVC Html.RadioButton - asp.net-mvc-3

Question

I am trying to use this example:
<label><input type="checkbox" data-bind="checked: displayMessage" /> Display message</label>
<div data-bind="if: displayMessage">Here is a message. Astonishing.</div>
<script type="text/javascript">
ko.applyBindings({
displayMessage: ko.observable(false)
});
</script>
My question is how can display the message if the following RadioButton is checked.
<%= Html.RadioButton("answer", qm.DynamicQuestions[index].Answer_A, (qm.LearnerAnswers[index] == qm.DynamicQuestions[index].Answer_A))%><%= Html.Encode( qm.DynamicQuestions[index].Answer_A) %>
I would appreciate your suggestions.

Answer 1

I'm guessing that you want something like this
http://jsfiddle.net/gonefishern/ktcY5/
<ul data-bind="foreach: questions">
<li>
<span data-bind="text: description"></span>
<ul data-bind="foreach: availableAnswers">
<li>
<label>
<input type="radio" data-bind="value: value, checked: checked, attr: {name: $parent.id }" />
<span data-bind="text: value"></span>
</label>
</li>
</ul>
</li>
</ul>
var questions = [{
id: 'ID1',
description: ko.observable('Should I answer this?'),
availableAnswers: [{
value: 'Yes',
checked: ko.observable('Yes')
}, {
value: 'No',
checked: ko.observable(false)
}]
},{
id: 'ID2',
description: ko.observable('How about answering this?'),
availableAnswers: [{
value: 'Yes',
checked: ko.observable()
}, {
value: 'No',
checked: ko.observable('No')
}]
}];
var vm = {
questions: questions,
}
ko.applyBindings(vm);