A.I. Explanation:

First sentence: Why this is the first line? This paragraph is the first because it introduces the main topic of the text. It talks about the open sea and dreams of sailing. This is a broad overview of the subject. It does not refer to any previous information. Why other lines are not chosen? Paragraph 2 starts with 'Signing up' which is not independent because it needs context. Paragraph 3 starts with 'Mastering' which also needs context. Paragraph 4 starts with 'With each voyage' which refers back to previous ideas. All these do not stand alone.

Concluding sentence: Why this is the last line? This paragraph is the last because it wraps up the ideas. It shows the result of learning to sail and how it leads to freedom and discovery. This gives a clear ending to the text.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects to Paragraph 1 because it follows the idea of dreams of sailing. The phrase 'Signing up for sailing lessons' shows the next step after dreaming about sailing.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects to Paragraph 2 because after stepping onto the boat, the next step is learning the skills of sailing. This shows a logical order of learning.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects to Paragraph 3 because after learning the basics, the next step is going on voyages. This shows a progression from learning to gaining confidence.