When scientific journals began to offer full online access to their articles in addition to the traditional printed volumes, scientists gained access to more journals and easier access to back issues. Surprisingly, this did not lead to a broader variety of articles being cited in new scientific articles. Instead, it led to a greater tendency among scientists to cite the same articles that their fellow scientists cited. Which one of the following, if true, most helps to explain the surprising outcome described above? ['Several new scientific journals appeared at roughly the same time that full online access to scientific articles became commonplace.', 'Online searching made it easier for scientists to identify the articles that present the most highly regarded views on an issue, which they prefer to cite.', 'Scientists who wrote a lot of articles were the most enthusiastic about accessing journal articles online.', 'Scientists are more likely to cite articles by scientists that they know than they are to cite articles by scientists they have never met, even if the latter are more prominent.']