By Chris Coyier
When you add a multiple choice field to a form, by default, the first choice is selected. You may or may not want that for your field on your form. You can select a different default option by clicking the radio button next to a different choice, or turn off the default choice entirely by clicking the active radio button.
Note that without a default choice, no answer is still a valid choice by the user unless you specifically mark the field as required. Also note turning on and off defaults works the same way with checkbox fields.
Here's a quick video demo:
Thanks to Eric Hansen for the idea on this quick tip!