A.I. Explanation:

First sentence: Why this is the first line? This paragraph is the first sentence because it introduces the main topic of zoos. It gives a broad overview of what the text will discuss. It does not use any pronouns or definite articles that need prior context. Why other lines are not chosen? Paragraph 2 starts with 'Wild animals', which is a specific subject and does not stand alone. Paragraph 3 starts with 'The Roman emperor', which uses 'the' and assumes prior knowledge. Paragraph 4 starts with 'In fact', which is a transitional phrase and does not stand alone.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it wraps up the discussion about zoos. It summarizes the negative aspect of zoos, showing the overall theme of the text.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): This pair connects because the second sentence explains where the animals in the first zoos came from. It shows a logical order of ideas.
• Pair 2 (Paragraph 2 → Paragraph 3): This pair connects because the second sentence gives an example of animals that were kept in zoos. It shows a broader to specific strategy.
• Pair 3 (Paragraph 3 → Paragraph 4): This pair connects because the fourth sentence gives a contrast to the previous sentence. It shows how the situation of animals in zoos changed.