The phrase "brought on" (Line 1, Para 4. ) most probably means _________.

A．was unique in evolution
B．evolved out of the low-oxygen environment hundreds of million years ago
C．is hard to explain
D．caused their extinction

A．scholarship will be a sheer private communication among scholars
B．the authorship will have to be shared by many collaborators in the world
C．scholarly writing can be a public event with the involvement of many scholars
D．scholarly writing can be a dynamic process and it will be more difficult to have a final result