A.I. Explanation:

First sentence: Why this is the first line? This paragraph is the first sentence because it gives a general statement about Alaska. It does not need another sentence for context. It introduces the topic of Alaska's natural features. This follows the rule of Topic Sentence. 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 'To the west', which is a specific reference and does not stand alone. Paragraph 3 uses 'Alaska was bought', which is specific and assumes prior knowledge. Paragraph 4 starts with 'Soon after', which indicates a continuation of thought. Paragraph 5 uses 'Alaska is also', which refers back to Alaska and does not stand alone.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it summarizes important points about Alaska's resources and statehood. It wraps up the discussion about Alaska, following the rule of Conclusive Words.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects to Paragraph 1 because it provides geographical context. The sentence starts with 'To the west', which shows a logical order of location related to Alaska.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 follows Paragraph 2 because it explains a historical fact about Alaska's relationship with Russia. This shows a logical order of events.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects to Paragraph 3 because it continues the story of Alaska's history. The phrase 'Soon after' shows a chronological order of events.
• Pair 4 (Paragraph 4 → Paragraph 5): Paragraph 5 follows Paragraph 4 because it adds more information about Alaska's resources. This shows a broader to specific strategy, where the general topic of resources is elaborated.