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. It tells us about the goal of the marine biologists and economists. This is an introductory sentence that sets the stage for what follows. It does not refer to any previous information, which makes it independent. Why other lines are not chosen? The other paragraphs are not chosen as the first sentence because they do not stand alone. For example, Paragraph 2 starts with 'They', which is a pronoun that refers back to a previous subject. Paragraph 3 also starts with 'These', which is not independent. Paragraph 4 uses 'The results', which assumes prior knowledge of the results.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it wraps up the text by stating the results of the analysis. It summarizes the work done by the marine biologists and economists, providing closure to the topic.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects with Paragraph 1 because it continues the idea of the work done by the marine biologists and economists. This shows a logical order of actions taken after they joined forces.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects with Paragraph 2 because it gives specific examples of the numbers they crunched. This follows the broader statement in Paragraph 2 with specific details, showing a general to specific strategy.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects with Paragraph 3 because it presents the outcome of the work described in Paragraph 3. This shows a logical order from the details of their work to the results.