A.I. Explanation:

First sentence: Why this is the first line? This paragraph is the first because it introduces the main idea of Copernicus. It does not need another sentence for context. It gives a broad overview of when he had his main idea. This follows the rule of Topic Sentence. Why other lines are not chosen? Paragraph 2 starts with 'For years,' which is a conjunction. Paragraph 3 starts with 'The historic book,' which uses the definite article 'the' and assumes prior knowledge. Paragraph 4 starts with 'According to legend,' which is also a conjunction.

Concluding sentence: Why this is the last line? This paragraph is the last because it wraps up the story of Copernicus. It gives a final detail about his life and the book. This follows the rule of Conclusive Words.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects to Paragraph 1 because it continues the story of Copernicus. It shows what happened after he had his main idea. This follows the Logical Order rule.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 follows Paragraph 2 because it explains what happened with his work. It shows that the book was not published until after he died. This shows a Cause and Effect Relationship.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects to Paragraph 3 because it tells what happened to Copernicus after the book was published. It shows a logical order of events.