A.I. Explanation:

First sentence: Why this is the first line? This paragraph is the first line because it introduces the main topic. It tells us about a big event that happened a long time ago. This is a clear start to the story. It does not need any other sentence to understand it. It does not use any words that need prior context. Why other lines are not chosen? The other paragraphs are not chosen because they do not stand alone. For example, Paragraph 2 starts with "Not long afterward," which shows it needs the first paragraph for context. Paragraph 3 starts with "Scientists don’t know," which also needs earlier information. Paragraph 4 starts with "The finding comes from," which refers to something before it. Paragraph 5 starts with "These fossils of ancient fish," which needs prior knowledge about the fossils.

Concluding sentence: Why this is the last line? This paragraph is the last line because it gives a final detail about the topic. It wraps up the information about the fossils. It does not need more information after it. It shows the end of the discussion about the findings.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects with Paragraph 1 because it uses the phrase "Not long afterward." This shows a clear time link. The second paragraph tells us what happened after the asteroid hit. This is a logical order of events.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects with Paragraph 2 because it talks about what scientists think about the event. It shows a cause and effect relationship. The death of the dinosaurs leads to scientists trying to understand when it happened.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects with Paragraph 3 because it explains where the information comes from. The phrase "The finding comes from" shows that the analysis of bones is related to the scientists' thoughts about the season.
• Pair 4 (Paragraph 4 → Paragraph 5): Paragraph 5 connects with Paragraph 4 because it gives more detail about the bones. The phrase "These fossils of ancient fish" shows what the analysis is about. This is a broader to specific strategy.