Explanation:

Only III is strong. The lure of earning private tuitions reduces the efforts and devotion of the teachers towards the students in schools. So, if tuitions are banned, students can benefit from their teachers' knowledge in the school itself. So, argument III holds strong while I does not. However, a person cannot be barred from earning more just because he already has a good salary. So, argument IV is vague. Further, the unemployed people thriving on tuitions can survive with the school teachers holding tuitions too, if they are capable enough to guide the students well. So, argument II also does not hold strong.