How can I get blank radio button options using collection_radio_buttons in the simple-form gem?

How can I get blank radio button options using collection_radio_buttons in
the simple-form gem?

References

Reference NO 1

http://stackoverflow.com/questions/15165326/how-can-i-get-blank-radio-button-options-using-collection-radio-buttons-in-the-s

Reference NO 2

http://stackoverflow.com/questions/7498005/want-rails-simple-form-radio-button-to-display-text-thats-not-the-value

Reference NO 3

https://github.com/plataformatec/simple_form

Reference NO 4

https://groups.google.com/d/topic/twitter-bootstrap-stackoverflow/MqOkmaJNz-w

Reference NO 5

http://rubydoc.info/github/plataformatec/simple_form/master/SimpleForm/FormBuilder

Reference NO 6

http://asciicasts.com/episodes/234-simple-form

Reference NO 7

http://rails-guides.joefiorini.com/4_0_release_notes.html

Reference NO 8

http://blog.plataformatec.com.br/tag/form/