A.I. Explanation:

First sentence: Why this is the first line? This paragraph is the first sentence because it introduces the main topic of great white sharks. It gives a broad overview of who they are and their role as apex predators. This follows the rule of Topic Sentence. Why other lines are not chosen? The other paragraphs are not chosen because they do not stand alone. For example, Paragraph 2 starts with 'Their' which is a pronoun and needs context. Paragraph 3 starts with 'Nevertheless', which is a conjunction and shows a contrast. Paragraph 4 starts with 'These', which also needs prior context. All these reasons make them not independent.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it wraps up the discussion about the threats to great white sharks and their environment. It summarizes the main points and shows the broader impact of human activities. This follows the Summary Style rule.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects with Paragraph 1 because it gives more detail about the hunting strategies of great white sharks. This follows the Broader to Specific Strategy, where the first paragraph introduces the topic and the second paragraph provides specific information.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects with Paragraph 2 because it shows a problem that affects great white sharks. The word 'Nevertheless' is a connector that shows a contrast between their abilities and the threats they face. This follows the Connector Strategy.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects with Paragraph 3 because it explains the effects of overfishing and habitat destruction. It shows how these activities harm not just sharks but the whole marine ecosystem. This follows the Cause and Effect Relationship rule.