Creating a 'choose all that apply' or multiple choice question within the user form can be accomplished by utilizing the checkbox style of True/False question.

The True/False question type within the User Form now features two styles: dropdown and checkbox.  

Checkbox displays the prompt with only a single checkbox next to it where the volunteer either checks it or doesn't.  This allows for the creation of a series of True/False questions formatted in a way where a volunteer may "choose all that apply."  Technically each option would be its own question, but presented stylistically to the volunteer as a single list.

Best practice would be to introduce the list of options with the topic question as a Header prompt and instructions as the sub prompt:

Followed by each option as its own subsequent True/False checkbox prompt:

When viewing a user's profile, only the Question Name for checked boxes appear:

Within the User Roster report, all question names are displayed and a value is present: