Exclusive Choice.

Click the 'E' button next to your choice to make it exclusive. If a respondent selects an exclusive choice, this will deselect every other choice and select only that choice. This is perfect for choices like "None of the above" and is available in Choice, Rank, and Matrix question types, i.e. wherever respondents can select multiple choices.  

Question Editor

Here's how it looks in your question editor.

Question Preview

Here's how it looks in your question preview.