972 - Logical Reasoning

Question : Toughened hiring standards have not been the primary cause of the present staffing shortage in public schools. The shortage of teachers is primarily caused by the fact that in recent years teachers have not experienced any improvements in working conditions and their salaries have not kept pace with salaries in other professions.
Which of the following, if true, would most support the claims above?

1. Many teachers already in the profession would not have been hired under the new hiring standards.
2. Today more teachers are entering the profession with a higher educational level than in the past.
3. Some teachers have cited higher standards for hiring as a reason for the current staffing shortage.
4. Many teachers have cited low pay and lack of professional freedom as reasons for their leaving the profession.
5. Many prospective teachers have cited the new hiring standards as a reason for not entering the profession.