In general, jobs are harder to get in times of economic recession because many businesses cut back operations. However, any future recessions in Vargonia will probably not reduce the availability of teaching jobs at government-funded schools. This is because Vargonia has just introduced a legal requirement that education in government-funded schools be available, free of charge, to all Vargonian children regardless of the state of the economy, and that current student-teacher ratios not be exceeded.

Which of the following, if true, most strengthens the argument?

1. The current student-teacher ratio at Vargonia’s government-funded schools is higher than it was during the most recent period of economic recession.
2. During recent periods when the Vargonian economy has been strong, almost 25 percent of Vargonian children have attended privately funded schools, many of which charge substantial fees.
3. Nearly 20 percent more teachers are currently employed in Vargonia’s government-funded schools than had been employed in those schools in the period before the last economic recession.
4. Teachers in Vargonia’s government-funded schools are well paid relative to teachers in most privately funded schools in Vargonia, many of which rely heavily on part-time teachers.
5. During the last economic recession in Vargonia, the government permanently closed a number of the schools that it had funded.

本题选B的原因是否: 经济萧条时, 原入学私校的学生会转读公校; 而因为要保持teacher-student ratio不能增加, 所以公校会扩招教师, 因此得出结论:any future recessions in Vargonia will probably not reduce the availability of teaching jobs at government-funded schools.

另外, A错的原因是什么呢?