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 zoos were like in the past. It does not use any words that need prior context. Why other lines are not chosen? The other paragraphs are not chosen because they do not stand alone. For example, Paragraph 2 starts with 'Wild animals', which needs context. Paragraph 3 starts with 'The Roman emperor', which also needs context. Paragraph 4 starts with 'In fact', which shows it is not independent.

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

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects with Paragraph 1 because it continues the topic of zoos. It explains where the animals in zoos came from. This shows a logical order of ideas.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects with Paragraph 2 because it gives examples of animals that were taken as tribute. This is a broader to specific strategy, moving from a general idea to specific examples.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects with Paragraph 3 because it shifts the focus to the condition of animals in zoos. It shows a contrast between the past and the present situation of animals.