Radio option buttons

Hi,

I want to design a survey to email out to people to complete. I am using word 2007 to do this. I have several questions in which there is only one answer to be given. Therefore I wanted to use option buttons which allow only one answer. How do I set this up so that each question has the option buttons. I find that at the moment I can only select one option button in the whole document. I need to allocate or group the option buttons to each question, so that for each question one option button can be picked, rather than what is happening now - where only one option button can be selected in the whole document.

Please help.

Thanks
Jules