Which of the following does not affect pollution levels in the Great Barrier Reef?

a. tourism

b. offshore drilling

c. land-based industries

d. overfishing

B. Offshore drilling. The Great Barrier Reef is one of the most visited natural wonders in the world and one of the most at-risk of being completely lost by climate change. Offshore Drilling has been banned by the Australian government within the vicinity of the Great Barrier Reef in an effort to protect it. There are however, many other problems including land-based industries releasing harmful gasses in the air that accelerate global warming causing the polar ice caps to melt and increase the ocean's temperatures. The reef's popularity is also harmful to it as well, with littering, overfishing, and human contact damaging the ecosystem of the natural wonder.

The answer would be offshore drilling