A.I. Explanation:

First sentence: Why this is the first line? This paragraph is the first line because it introduces Harriet Tubman and her background. It uses the rule of Topic Sentence because it gives a clear idea of who she is and what she did. It does not need any other sentence for context. 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 escaping slavery,' which needs context from the first sentence. Paragraph 3 starts with 'By doing this,' which also needs the previous sentence. Paragraph 4 starts with 'As a result,' which shows it is a conclusion and needs earlier information.

Concluding sentence: Why this is the last line? This paragraph is the last line because it wraps up the story of Harriet Tubman. It uses the rule of Conclusive Words because it summarizes her life and shows her lasting impact.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects with Paragraph 1 because it continues the story of Harriet Tubman. It uses the Logical Order rule because it explains what she did after her early life.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects with Paragraph 2 because it explains the result of her actions. It uses the Cause and Effect Relationship rule because it shows how her bravery helped many people.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects with Paragraph 3 because it talks about the impact of her actions. It uses the Conclusive Words rule because it summarizes her legacy and shows the importance of her work.