Answer:
Excessive texting can be harmful to your physical health.
Explanation:
The topic sentence is a sentence that summarizes the main idea of a paragraph or a larger part of the text (such as the Introduction, like in this case). It is usually the first sentence of the text segment.
We can see that the paragraph named <em>Main fact 1 </em>discusses ways excessive texting can negatively affect your physical health. Its topic sentence should summarize that idea, and that's why the fourth option is the correct one.
We can help what are the lines
