We are looking for the best conclusion for the final paragraph.
B is incorrect because it makes it seem like the problems described in the passage were due to foresters not recognizing the dangers posed by excess fuel in forests, and resistance in the forestry community. But nothing in the passage was about forests not recognizing dangers — we were told that the problem was “the relative success of fire-suppression efforts.†The only information we got about the forestry community was about selective timber harvesting, which would help solve the problem, rather than indicate that foresters don’t recognize the danger.
C is correct because it makes clear that while there are ameliorative policies that are possible, which are the very policies the final paragraph talks about, large fires will still be a threat because the policies take time. It neatly wraps up the paragraph and connects it back to the main problem described in the passage, and that it is why it most logically completes the paragraph.