A.I. Explanation:

First sentence: Why this is the first line? This paragraph is the first because it introduces the main topic. It talks about the problems of ancient Romans, which is the main idea of the text. It does not need other sentences to understand it. It does not use any words that need prior context. Why other lines are not chosen? Paragraph 2 starts with "Even in the 1st century AD" which needs context from before. Paragraph 3 starts with "The rooms were usually small" which refers to specific rooms and needs prior information. Paragraph 4 starts with "Also, fires were common" which uses "also" to connect to something before.

Concluding sentence: Why this is the last line? This paragraph is the last because it wraps up the discussion. It shows how different the living conditions were for the wealthy compared to the poor. It gives a final thought on the topic, making it a good conclusion.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects to Paragraph 1 because it continues the topic of high-rise blocks. It gives more information about the limits on these buildings. This shows a logical order of ideas.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects to Paragraph 2 because it describes the conditions in the high-rise blocks. It gives specific details about the small rooms and high rents, which follow the general idea of limits on building height.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects to Paragraph 3 because it continues to talk about the problems of living in high-rise blocks. It mentions fires as another issue, which adds to the unpleasant living conditions.