A.I. Explanation:

First sentence: Why this is the first line? This paragraph is the first sentence because it introduces the main topic of the drive. It sets the stage for what will happen next. It does not use any pronouns or definite articles that refer to previous ideas. This makes it independent and a good start. Why other lines are not chosen? Paragraph 2 starts with "To spread the word," which suggests it is not independent. Paragraph 3 starts with "Volunteers were crucial," which also assumes prior context. Paragraph 4 starts with "The drive concluded," which refers to something that has already happened.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it wraps up the whole event. It shows the final action of sorting the books, which concludes the story of the drive.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects to Paragraph 1 because it shows the next step after setting a date. It uses the connector "To spread the word" to show how they informed the community.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 follows Paragraph 2 logically. After spreading the word, volunteers helped with the event. This shows a clear flow of ideas.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects to Paragraph 3 because it describes what happened after the volunteers helped. It shows the result of their work.