Answer:
In sentence 4, change “thing” to “barrier.”
Step-by-step explanation:
Text precision means making the text more specific or understandable, making the explanation easy to comprehend by the readers. It can also be the process of making the detail exact, accurate, correct, etc.
In the given text, the excerpt talks of cleaning garbage in oceans by a newly developed system. And by changing the word "thing" used in sentence 4 to "barrier", the readers will know what the author was referring to or talking about.
Thus, the correct answer is the fourth option.