For multiple choice questions(Multiple answers allowed), the sum of the score ratios of each correct answer must be 100%.
Set the score ratio to '-100%'.
EX. 4 answers(2 correct answers / 2 incorrect answers)
→ Correct answer 50% / Correct answer 50% / Incorrect answer -100% / Incorrect answer -100%
EX. 5 answers(3 correct answers / 2 incorrect answers)
→ Correct answer 33.333% / Correct answer 33.333% / Correct answer 33.333% / Incorrect answer -100% / Incorrect answer -100%
(Note)