A.I. Explanation:

First sentence: Why this is the first line? This paragraph is the first because it introduces a big idea. It tells us that something serious is happening. It does not need other sentences to understand it. It does not use words that need earlier context. Why other lines are not chosen? Paragraph 2 starts with 'The summer of 2019', which needs context. Paragraph 3 starts with 'Festivals', which is not a general idea. Paragraph 4 starts with 'It was a time', which uses a pronoun that needs earlier sentences.

Concluding sentence: Why this is the last line? This paragraph is the last because it wraps up the ideas. It reflects on the past and shows how things have changed. It gives a clear end to the discussion.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects to Paragraph 1 because it talks about time. The phrase 'feels like a distant memory' shows that we are looking back. This is a logical order.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects to Paragraph 2 because it gives details about the summer of 2019. It explains what was happening during that time. This is a broader to specific strategy.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects to Paragraph 3 because it continues the idea of gatherings. It explains that people could gather without fear. This shows a logical order.