First sentence: Why this is the first line? This paragraph is the first line because it introduces the main topic, which is the Bajau Tribe. It gives a broad overview of where they come from without going into details. This follows the rule of Topic Sentence. Why other lines are not chosen? Paragraph 2 starts with 'These sea nomads,' which uses a pronoun that refers back to the Bajau Tribe, so it cannot be the first line. Paragraph 3 starts with 'Studies have shown,' which is not an independent statement because it needs context. Paragraph 4 starts with 'This ability,' which also uses a pronoun. Paragraph 5 starts with 'This ability,' which again uses a pronoun. All these reasons make them not independent.

Concluding sentence: Why this is the last line? This paragraph is the last line because it wraps up the main ideas about the Bajau Tribe. It summarizes the advantages of their genetic adaptation and how it helps them in free-diving. This follows the rule of Summary Style.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects with Paragraph 1 because it continues the topic of the Bajau Tribe. It uses the term 'sea nomads' to refer back to the Bajau Tribe, showing a clear link. This follows the Noun Pronoun Rule.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects with Paragraph 2 because it introduces a new idea about the Bajau Tribe. It explains that they have a genetic adaptation, which is related to their lifestyle of spearfishing. This follows the Logical Order rule.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects with Paragraph 3 because it explains the effects of the genetic adaptation mentioned in Paragraph 3. It shows how this adaptation helps the Bajau Tribe, following the Cause and Effect Relationship rule.
• Pair 4 (Paragraph 4 → Paragraph 5): Paragraph 5 connects with Paragraph 4 because it discusses the advantage of the ability mentioned in Paragraph 4. It shows the benefit of having a larger spleen size, following the Broader to Specific Strategy.