A.I. Explanation:

First sentence: Why this is the first line? This paragraph is the first line because it introduces the main topic. It talks about the Aboriginal people and the miners. It gives a broad overview of the history of Coober Pedy. This is why it is the opening sentence. Why other lines are not chosen? The other paragraphs are not chosen because they do not stand alone. For example, Paragraph 2 starts with 'As a result' which shows it needs more context. Paragraph 3 starts with 'This has continued' which also needs earlier information. Paragraph 4 starts with 'Among the local public buildings' which is specific and needs a topic. Paragraph 5 starts with 'Opals can be seen' which is too specific and does not introduce the main topic.

Concluding sentence: Why this is the last line? This paragraph is the last line because it wraps up the topic. It gives a final detail about the hotels. The sentence does not need more information and concludes the discussion about Coober Pedy.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects with Paragraph 1 because it continues the story of the miners. The phrase 'As a result' shows a cause and effect relationship. The miners moved to Coober Pedy because of the opal, and now they live underground because of the heat.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects with Paragraph 2 because it shows what happened next. The phrase 'This has continued' shows that the living underground is a trend that keeps going. It logically follows the choice of miners to live underground.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects with Paragraph 3 because it gives examples of what is underground. The phrase 'Among the local public buildings' shows specific details about the modern town that was mentioned in the previous paragraph.
• Pair 4 (Paragraph 4 → Paragraph 5): Paragraph 5 connects with Paragraph 4 because it talks about the hotels mentioned before. The hotels are part of the public buildings, and now it shows what can be found in those hotels, which is opals.