A.I. Explanation:

First sentence: Why this is the first line? This paragraph is the first line because it introduces the main topic of the text. It gives a broad overview of what the text will be about, which is organizing a garage sale. It does not use any specific details or references to other sentences. Why other lines are not chosen? The other paragraphs are not chosen because they do not stand alone. For example, Paragraph 2 starts with 'After selecting,' which means it needs more context. Paragraph 3 uses 'Once everything,' which also needs prior information. Paragraph 4 starts with 'The final step,' which suggests it is not the beginning. All these sentences are dependent on previous ideas.

Concluding sentence: Why this is the last line? This paragraph is the last line because it wraps up the process of organizing a garage sale. It uses the phrase 'The final step,' which signals that this is the conclusion of the actions needed. It brings together all the steps mentioned before.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects to Paragraph 1 because it follows the idea of organizing a garage sale. The first paragraph introduces the topic, and the second paragraph gives a specific action to take after deciding to have a sale. This shows a logical order from general to specific.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects to Paragraph 2 because it continues the process of preparing for the sale. After labeling items, the next step is to advertise. This shows a clear logical order of actions.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects to Paragraph 3 because it describes the last action needed before the sale. After advertising, the final step is to set up the items. This shows a clear sequence of steps.