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 about how mountains are formed. It is a general statement that does not need other sentences for context. It does not start with a conjunction or use pronouns. Why other lines are not chosen? Paragraph 2 starts with 'Molten', which is not independent. Paragraph 3 starts with 'Many', which is not independent. Paragraph 4 starts with 'Other', which is not independent. Paragraph 5 starts with 'This', which is not independent.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it summarizes the main idea of the text. It wraps up the discussion about how mountains are formed by explaining the underground forces involved.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects with Paragraph 1 because it explains how some mountains are formed. This is a logical order where the process of volcano formation follows the introduction of volcanoes.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects with Paragraph 2 because it gives an example of where volcanoes can be found. This shows a broader to specific strategy, where the general process of lava cooling leads to specific islands.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects with Paragraph 3 because it introduces another way mountains can form. This shows a logical order where different types of mountain formation are discussed.
• Pair 4 (Paragraph 4 → Paragraph 5): Paragraph 5 connects with Paragraph 4 because it explains the process of how underground forces create mountains. This shows a cause and effect relationship.