This has been said before, when the multianswer box is check in what was a multiple choice Lesson question type, the evaluation changes. There was a recent post in MDL-7683, please vote for an improvement.
All the correct answers must have the same jump and response. All the wrong answers must have the same jump and response if the teacher wants all students to have consistant results. That is how it functions.
MoodleDocs (I just put it in bold) tries to be clear because I did not get it. A couple of years ago (now), I created a 6 answer multianswer question 3 or 4 times, placed the correct and wrong answers in a different physical order in each question in edit mode. I think there is a logic to the jump and response that Lesson selects when the quesiton is judged correct or wrong but I will let Joseph explain it
The Quiz question type is not much better. A student's score is calculated by adding up all the answers they selected. So if the teacher does not put a negative on an answer, the student can select all the answers, see they selected 2 wrong answers but get 100% credit because they selected both the correct answers. If the teacher puts a negative on the wrong answers, then when a student selects only wrong answers, they will get -100% of the score. Don't know what happens if there are 6 answers, 2 right and 4 wrong
Sure this does not help. Best to all Chris