A.I. Explanation:

First sentence: Why this is the first line? This paragraph is the first because it introduces the main topic of the text. It talks about the idea of changing the rooftop into a green space. This is a broad overview of what the text will discuss. It does not use any specific details or references to previous information. Why other lines are not chosen? Paragraph 2 starts with 'Researching' which is not a general statement. Paragraph 3 starts with 'Subsequently' which is a conjunction. Paragraph 4 starts with 'The installation' which uses the definite article 'the' and assumes prior knowledge. Paragraph 5 starts with 'Looking' which is not a general statement.

Concluding sentence: Why this is the last line? This paragraph is the last because it wraps up the text. It reflects on the feelings of pride after completing the garden. It brings together the earlier points about the process of creating the rooftop garden.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): This pair connects because the first paragraph introduces the idea of creating a green space. The second paragraph follows logically by explaining the first step in this process, which is researching plants. This shows a logical order of thought.
• Pair 2 (Paragraph 2 → Paragraph 3): This pair connects because the second paragraph talks about researching plants. The third paragraph continues this thought by explaining the next action taken, which is buying containers and soil. This shows a clear progression of steps.
• Pair 3 (Paragraph 3 → Paragraph 4): This pair connects because the third paragraph discusses buying containers and soil. The fourth paragraph then explains another important step, which is installing an irrigation system. This shows a logical order of actions.
• Pair 4 (Paragraph 4 → Paragraph 5): This pair connects because the fourth paragraph talks about the irrigation system, which is part of the gardening process. The fifth paragraph concludes by expressing pride in the completed garden. This shows a logical flow from action to reflection.