To determine how the text structure effectively meets the author's purpose, consider the options provided. The passage likely aims to raise awareness about the magnitude of the Great Pacific Garbage Patch and the significance of plastic waste in our oceans.
The most effective choice would be "By explaining the significance of plastic waste in major bodies of water." This aligns with the author's purpose of informing readers about the critical issue of plastic pollution and its impact on the environment.
If additional context reveals that the passage emphasizes new findings compared to earlier research, then "By comparing prior research with the latest findings by international scientists" could also be a valid answer, depending on the specific content of the text. However, without that context, the first option about explaining significance is more straightforwardly aligned with raising awareness about plastic waste.