The sixth paragraph of the passage states that "Katz doesn't dismiss the notion that there is something different about today's digital technologies — something that could affect an even broader range of work." In the context of this sentence, the "range" of work being discussed means the scope of work or all the various kinds of work.
Choices A, C, and D are incorrect because in the context of the sentence, the "range" of work being discussed means the array or scope of work, not a physical delineation like a region (choice A) or distance (choice C), or the professional position of those who perform particular jobs (choice D).