Some writing teachers believe that writing is best accomplished by

Some writing teachers believe that writing is best accomplished by creating a rough draft very quickly, and then editing and re-editing through many drafts. Recently, however, a survey of best-selling authors found that these authors most frequently write very slowly, spending more time on the first draft, and then publish the manuscript with little editing. Authors of books that are not best-sellers write the first draft more quickly, and then rewrite and re-edit. This shows that writing more slowly is the most effective method for producing high-quality manuscripts.

Which of the following is an assumption on which the conclusion is based?

A. Writing quickly and then rewriting many drafts of a manuscript is not useful in creating certain types of manuscripts.
B. Best-selling authors are able to write either quickly or slowly, and create many or few drafts of a manuscript.
C. At least some writing teachers lead their students to write slow first drafts with little editing.
D. Best-selling authors write slowly and create few drafts in creating the majority of their manuscripts.
E. Best-selling authors create higher quality manuscripts than do authors of books that are not best-sellers.