A. 80% (of the 30 showing good behavior)
B. 20% (of the 30 showing good behavior)
C. 0% (of the 30 showing bad behavior)
D. 100% (of the 30 showing bad behavior)
This question is asking you to make to draw some conclusions yourself. Including the total number of students, and the assumption that all of the students with good or bad behavior are included in the table.
Please let me know if you have any questions.