Which is most seriously weakens the scientists argument

Question

Assignment:

Scientist: Over the last two decades, the number of retractions scientific journals have had to publish has increased tenfold, while the number of articles published annually by these journals has increased only slightly. This is indicative of an alarming increase in the incidence of scientists' cutting corners in their research, which is presumably due to the enormous pressure on scientists to publish in order to succeed professionally.

Which one of the following, is true, most seriously weakens the scientist's argument?

1. It has become more difficult for scientists to secure jobs over the last two decades and to hold on to those jobs once they are secured.
2. Publication rates are a major factor in obtaining government grants, which account for an increasing proportion of scientists' income.
3. The number of journal articles available on the Internet has increased substantially over the last two decades, allowing for greater scrutiny of articles after publication.
4. Credit for a scientific advance is generally given to the scientist who publishes the finding first, even when other scientists have developed the same idea.
5. Some of the articles retracted in the last few years had problems due to scientific misconduct, but most had problems attributable to unintentional scientific error.