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 text. It talks about the beginning of the task and shows the writer's feelings about it. This is a general statement that does not need other sentences for context. It does not start with a conjunction or use pronouns that refer to other ideas. Why other lines are not chosen? The other paragraphs are not chosen because they do not meet the criteria for being independent. For example, Paragraph 2 starts with 'Before starting,' which shows it needs context. Paragraph 3 starts with 'Scanning each book,' which also needs context. Paragraph 4 starts with 'The final step,' which refers to something already mentioned.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it wraps up the process. It talks about the final step in the task of digitising books. It summarizes the actions taken and shows the result of the work.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects with Paragraph 1 because it follows the logical order of the process. After feeling daunted, the writer explains what they did before starting the task. This shows a clear flow of ideas.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects with Paragraph 2 because it continues the logical order. After researching, the writer explains the next step, which is scanning the books. This shows a clear progression in the process.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects with Paragraph 3 because it shows the next step after scanning. After the careful scanning process, the writer explains what they did last, which is cataloguing the books. This shows a clear flow of actions.