A.I. Explanation:

First sentence: Why this is the first line? This paragraph is the first sentence because it introduces the main topic of camping. It talks about economy as a reason for camping. This is a general statement that does not need other sentences for context. It does not start with a conjunction or use pronouns. Why other lines are not chosen? Paragraph 2 starts with 'But', which is a conjunction. Paragraph 3 uses 'it', which is a pronoun that refers back to something else. Paragraph 4 uses 'the', which assumes prior knowledge of 'equipment'. So, they cannot be the first sentence.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it wraps up the discussion about camping. It gives a final thought about the equipment and how it relates to camping. This shows the overall theme of the text.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects to Paragraph 1 because it uses 'But' as a connector. This shows that it is giving a contrast to the idea of economy being the only reason for camping.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 continues from Paragraph 2 by giving an example of a situation in camping. This shows a logical order where the idea of other reasons for camping leads to a specific example.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects to Paragraph 3 because it shifts the focus back to the equipment of camping. This shows a broader topic that relates to the previous example.