A.I. Explanation:

First sentence: Why this is the first line? This paragraph is the first sentence because it asks a question. It introduces the main topic of the text, which is about researchers and their ideas. It does not need another sentence for context. This follows the rule of Topic Sentence. Why other lines are not chosen? The other paragraphs are not chosen because they do not stand alone. For example, Paragraph 2 starts with 'Perhaps' which is a conjunction. Paragraph 3 starts with 'But' which is also a conjunction. Paragraph 4 starts with 'To wit,' which is a transitional phrase. All these words show that these sentences need more context to make sense.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it wraps up the main ideas. It gives a conclusion about the importance of facts and new ideas. This follows the Conclusive Words rule.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects with Paragraph 1 because it gives a possible answer to the question in Paragraph 1. This follows the Question→Answer Structure rule.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects with Paragraph 2 because it gives more information about the worries mentioned in Paragraph 2. This follows the Broader to Specific Strategy rule.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects with Paragraph 3 because it talks about the importance of facts and new ideas. This follows the Logical Order rule.