The correct answer is B. It is stated directly in the first paragraph.
The central idea of the article is that the journalism industry is experiencing a significant lack of diversity, particularly in leadership roles held by women and racial minorities. This main point is clearly articulated in the first paragraph, where the statistics regarding the representation of women and minorities in supervisory positions in journalism are presented. As a result, the article's primary argument is established right at the beginning, making this option the most accurate.