A.I. Explanation:

First sentence: Why this is the first line? This paragraph is the first because it introduces the main topic of the tea ceremony. It gives a broad overview of what the text will discuss. It does not use any pronouns or definite articles that need prior context. Why other lines are not chosen? Paragraph 2 starts with "Before the ceremony begins," which refers to the ceremony and needs context. Paragraph 3 starts with "Upon entering the tearoom," which also needs context. Paragraph 4 starts with "Finally," which shows it is not independent.

Concluding sentence: Why this is the last line? This paragraph is the last because it concludes the sequence of events in the tea ceremony. It wraps up the main idea by showing the final action of serving tea.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects to Paragraph 1 because it talks about what happens before the ceremony. This shows a logical order of events.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 follows Paragraph 2 because it describes what guests see after they cleanse themselves. This shows a clear flow of ideas.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects to Paragraph 3 because it describes what happens after the preparation. This shows a logical order of events.