A.I. Explanation:

First sentence: Why this is the first line? This paragraph is the first sentence because it introduces the main topic of the text, which is about prize fighting and its differences from modern boxing. It sets the stage for the discussion without needing any prior context. This follows the rule of Topic Sentence. Why other lines are not choosen? The other paragraphs are not chosen because they do not stand alone. For example, Paragraph 2 starts with 'Boxing gloves,' which needs context. Paragraph 3 talks about contests but does not introduce the topic. Paragraph 4 mentions time allowed but does not start the main idea. Paragraph 5 refers to rules that need earlier information.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it wraps up the discussion about the history of boxing. It provides important information about the introduction of gloves and the rules, which concludes the topic. This follows the Conclusive Words rule.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects to Paragraph 1 because it continues the topic of prize fighting. It explains how the fighters fought, which is a detail that follows the general idea of Paragraph 1. This follows the Logical Order rule.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects to Paragraph 2 because it gives more details about the fights. It talks about the length of contests, which is a specific detail that follows the general information about fighting styles. This follows the Broader to Specific Strategy.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects to Paragraph 3 because it talks about the rules of the fights. It explains what happened after a fighter was knocked down, which is a detail that follows the information about the contests. This follows the Logical Order rule.
• Pair 4 (Paragraph 4 → Paragraph 5): Paragraph 5 connects to Paragraph 4 because it shifts to the introduction of boxing gloves and the rules. It shows how the sport changed over time after discussing the earlier rules. This follows the Topic Example rule.