Select All Correct is the question type for "which of these apply". Several options can be right, and the student ticks every one they think belongs.
Adding one
Type /sel, or pick Select All Correct from the + menu. It arrives with a Question field and two empty options.
Setting it up
1. Type the question. Say plainly that more than one answer may be right, so students do not stop at the first one they recognise. "Select all of the following that are noble gases" leaves no room for doubt.
2. Fill in the options, clicking Add answer for more.
3. Click the box beside every correct option. Unlike Multiple Choice these toggle independently, so you can mark as many as belong.
4. Set the marks with the + and - controls.
How it is marked, and why it matters here
All or nothing, on the whole set. The student earns the marks only if their ticks match your correct options exactly. One missed correct answer, or one extra wrong tick, scores zero. There is no partial credit.
This catches people out, so it is worth designing around:
Keep the option list short. Six options with four correct answers is a question almost everyone scores zero on, however well they understand the topic.
Allocate marks accordingly. A question that demands four simultaneous correct judgements is worth more than one mark.
If you want partial credit, split it up. Several True or False questions, one per statement, will give you a far more useful picture of what a class knows than one unforgiving Select All Correct.
You can still see exactly which options each student ticked, whatever they scored. See The Block Detail Drawer: per-student responses.