Questions: The Great Pacific Garbage Patch will be difficult to physically clean up because a. it lies in international waters b. no single nation is responsible for creating it c. filtering out the plastic will also remove plankton d. all of the above

The answer is D: all of the above.

Explanation for each option:

a. It lies in international waters: This is correct because the Great Pacific Garbage Patch is located in international waters, which complicates jurisdiction and responsibility for cleanup efforts.

b. No single nation is responsible for creating it: This is also correct. The garbage patch is a result of waste from multiple countries, making it difficult to assign responsibility to any single nation.

c. Filtering out the plastic will also remove plankton: This is correct as well. Any attempt to filter out the plastic debris risks removing plankton, which are crucial to the marine food web.

Since all the options are correct and contribute to the difficulty of cleaning up the Great Pacific Garbage Patch, the best answer is D: all of the above.