A.I. Explanation:

First sentence: Why this is the first line? This paragraph is the first sentence because it introduces the main topic, which is the Mona Lisa. It gives a broad overview of the subject without going into details. 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 'But', which is a conjunction. Paragraph 3 uses 'this work's', which refers back to the Mona Lisa, so it cannot be independent. Paragraph 4 also cannot stand alone as it refers to ideas from previous sentences.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it wraps up the discussion about the Mona Lisa. It gives a conclusion about the story of the Mona Lisa, which follows the rule of Conclusive Words.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects with Paragraph 1 because it asks a question about the Mona Lisa. This is a logical order because it follows the introduction of the topic with a question. This follows the rule of Question→Answer Structure.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects with Paragraph 2 because it answers the question asked in Paragraph 2. This shows a clear logical order from question to answer.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects with Paragraph 3 because it summarizes the reasons mentioned in Paragraph 3. This follows the rule of Summary Style, as it brings together the earlier points.