A.I. Explanation:

First sentence: Why this is the first line? This paragraph is the first sentence because it introduces the main idea about animals and their exploratory urge. It sets the stage for the discussion without needing any prior context. 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 'It depends,' which needs more context. Paragraph 3 starts with 'If they have put,' which is also not independent. Paragraph 4 starts with 'So long as,' which is a conditional phrase. Paragraph 5 starts with 'The non-specialists,' which refers back to a previous idea.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it wraps up the discussion about animals. It shows the difference between specialists and non-specialists. This follows the Conclusive Words rule.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects to Paragraph 1 because it explains why some animals have a stronger exploratory urge. This follows the Logical Order rule.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects to Paragraph 2 because it gives an example of specialization. This follows the Broader to Specific Strategy.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects to Paragraph 3 because it shows how some animals are satisfied with their specific needs. This follows the Cause and Effect Relationship rule.
• Pair 4 (Paragraph 4 → Paragraph 5): Paragraph 5 connects to Paragraph 4 because it contrasts the specialists with non-specialists. This follows the Contrast rule.