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, which is Greenland. It uses the rule of Topic Sentence. It gives a broad overview of what the text will be about without going into details. Why other lines are not chosen? The other paragraphs are not chosen because they do not stand alone. For example, Paragraph 2 starts with "Most of it" which needs context. Paragraph 3 starts with "The Norse Vikings" which also needs prior information. Paragraph 4 starts with "Eric the Red" which assumes knowledge of Greenland.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it provides a specific event related to Greenland. It wraps up the information about Greenland's history. It uses the Summary Style rule, bringing together earlier points about Greenland and its discovery.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects to Paragraph 1 because it gives more details about Greenland. It uses the Broader to Specific Strategy. The first sentence is general, and the second sentence explains more about the land.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects to Paragraph 2 because it talks about the discovery of Greenland. It uses the Logical Order rule. The second paragraph describes the land, and the third paragraph explains who found it.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects to Paragraph 3 because it gives a specific example of a person related to Greenland's history. It uses the Topic Example rule. The third paragraph talks about the Vikings, and the fourth paragraph gives an example of Eric the Red.