Check Radio Buttons and Checkboxes by Default
Problem Explanation
The checked attribute, exclusively usable with type="radio" and the type="checkbox", is a boolean attribute ( you can check the challenge about the required attribute, boolean aswell, at this link: use html5 to require a field).
As boolean attribute you simply have to add the word checked to the input HTML element you want to set checked by default (the challenge requires you to set by default the first of the checkbox and radio-buttons already present in the code).
Good luck!