So I originally chose (C) during preptest but was able to select in (E) when reviewing it. Here's my understanding:
Conclusion: Although travel writing has changed in this time, Anderson is too harsh on contemporary travel writers.
The first sentence is what the author purported to refute, and there's no explanation for how that view is formed and what it's based on. So (C) is incorrect.
"the general public is better traveled today than in the past" is used to show one advantage current writers have over the past ones, and it's counterbalanced by a disadvantage "a challenge far greater than the predecessors...", which forced the current writers to work more, hence "transform the task" as in (E).
The author goes on stating despite this disadvantage, the genre has survived and even flourished, which shows the talent of the current writer, and of course, shows that Anderson's criticism is overly harsh.
(A) if anything, the reasoning is backward, better traveled helped create good travel writing, not resulted from it.
(B) wider readership is out of scope
(D) nowhere did the author mention the travel writing flourishes "more today" than the past.