A.I. Explanation:

First sentence: Why this is the first line? This paragraph is the first sentence because it introduces the main topic about zoo animals' lives in the past. It gives a broad overview of the situation without going into details. It does not use any pronouns or definite articles that would need prior context. Why other lines are not chosen? Paragraph 2 starts with "The first zoo elephant..." which uses a definite article and assumes prior knowledge. Paragraph 3 starts with "Such solitary confinement..." which uses a pronoun that refers back to something not yet mentioned. Paragraph 4 starts with "In the past..." but it is not as general as the first sentence.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it concludes the discussion about the conditions of zoo animals. It summarizes the main point about the cruelty of solitary confinement, wrapping up the overall theme.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): This pair connects because the second paragraph gives a specific example of zoo animals, which follows the general statement in the first paragraph. This is a Broader to Specific Strategy.
• Pair 2 (Paragraph 2 → Paragraph 3): This pair connects because the third paragraph explains the conditions of zoos over time, linking back to the example of the elephant in the second paragraph. This shows a Logical Order of ideas.
• Pair 3 (Paragraph 3 → Paragraph 4): This pair connects because the fourth paragraph explains the cruelty of keeping animals alone, which relates directly to the miserable conditions mentioned in the third paragraph. This is a Cause and Effect Relationship.