Multiple choice shows a list of checkboxes, and participants tick every option that applies. Each option is a subquestion. Use it for questions like "Which devices do you use?" where more than one answer can be true.
Participants see the tip Select all that apply.
Click the purple + in the top bar. The question type picker opens.
Under Multiple choice, click Multiple choice. The question appears at the end of the current question group.
Click Your question here and type your question.
Click the first subquestion and type the option. Add subquestion below the last row adds another one. The red x removes a row, the handle next to it moves it.
Select the question to open its settings on the right.
Every option is stored on its own, for example Q009_SQ001, Q009_SQ002 for a question with the code Q009. A ticked option stores Y, an unticked one stays empty. In the export, each option is a column.
Add "None of these" as the last subquestion, turn on Question codes under View in the ... menu to see its code, for example SQ005, and enter that code in Exclusive option.
Each option is a column: Y means ticked, empty means not ticked. The export page can convert Y to 1. See Export your responses.