When Answer Order is set to Random for a test or quiz, multiple choice answers can be "anchored" to the bottom of the answer list and not randomized. This is useful for answers like “All of the above” or “None of the above,” which only make sense at the bottom of a list of answers.
When creating a test with random answer order, multiple choice questions will have a checkbox below each answer labeled Anchor Answer.
In this example, "Answer A," "Answer B," and "Answer C" will be randomized, while "All of the above" and "None of the above" will remain at the bottom. The following image is how the answers will appear to a student:
Please note that this feature is only for multiple choice questions. Multiple select questions can already achieve “All of the above” or “None of the above” by selecting every answer or none of the answers.