Limit the checkbox checked to only one item in IList

I have created a IList given as below:

[CultureSpecific]
[Display(Name = "Items", GroupName = PropertyGroupNames.Content, Order = 20)]
[EditorDescriptor(EditorDescriptorType = typeof(AnswerListPropertyDescriptor))]
[ListItems(4)]

public virtual IList<AnswerBlock> Answers { get; set; }

AnswerBlock is a class I have created:

public class AnswerBlock
{
[CultureSpecific]
[Display(Name = "Answer Text", GroupName = PropertyGroupNames.Content, Order = 10)]
public virtual string AnswerText { get; set; }

[CultureSpecific]
[Display(Name = "Correct Answer", GroupName = PropertyGroupNames.Content, Order = 20)]

public virtual bool IsCorrect { get; set; }
}

IsCorrrect is a type of a checkbox

I add multiple elements in the dropdownlist created due to IList

The problem is that II'm able to set true to multiple checkboxes present in the IList

I just want to limit it upto 1. i.e I should only be able to set 1 checkbox to true in IList.

Please help