Final answer:
Paragraph 8 is the most effective in addressing the existence of ocean garbage patches as it directly relates the accumulation of trash to its impact on animals and the pollution of both ocean and freshwater resources. The correct answer is option 8.
Step-by-step explanation:
The paragraph that most effectively develops the author's claims about the existence of ocean garbage patches is paragraph 8. This paragraph succinctly summarizes the problem of garbage accumulation in the ocean and its adverse effects on wildlife. It mentions how animals can be strangled by floating trash or mistake it for food, linking the problem directly to both ocean and freshwater pollution.