A.I. Explanation:

First sentence: Why this is the first line? This paragraph is the first line because it introduces the main event. It tells us when and where the event happens. It does not need other sentences to understand it. It is a general statement about the running of the bulls. Why other lines are not chosen? Paragraph 2 starts with 'This running of the bulls,' which needs context from the first sentence. Paragraph 3 starts with 'Most wear a common uniform,' which refers to the bulls but does not stand alone. Paragraph 4 starts with 'The white of the uniforms,' which also needs prior information to make sense.

Concluding sentence: Why this is the last line? This paragraph is the last line because it wraps up the discussion about the uniforms. It gives the meaning behind the colors, which is a good way to end the text.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects to Paragraph 1 because it explains what happens during the event. The phrase 'This running of the bulls' refers back to the event mentioned in Paragraph 1. This shows a clear flow of ideas.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects to Paragraph 2 because it describes what people wear during the event. The mention of 'Most wear a common uniform' follows the description of the running of the bulls, showing a logical order.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects to Paragraph 3 because it explains the colors of the uniforms. The phrase 'The white of the uniforms' directly relates to the uniforms mentioned in Paragraph 3, showing a clear connection.