A.I. Explanation:

First sentence: Why this is the first line? This paragraph is the first sentence because it introduces the main topic of communication in the past. It does not need another sentence for context. It sets up the theme of how messages were delivered before technology changed. Why other lines are not chosen? Paragraph 2 starts with "Communication was slow then," which refers back to the previous idea, so it is not independent. Paragraph 3 starts with "With increasing advancements," which also needs context from earlier sentences. Paragraph 4 uses "One common method," which assumes knowledge of the topic. Paragraph 5 starts with "It is one of the fastest ways," which refers back to the previous idea of sharing information.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it wraps up the main idea of the text. It summarizes the importance of fast communication in business and professional settings.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects with Paragraph 1 because it continues the idea of how messages were delivered in the past. It shows the logical order of how communication was slow.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 follows Paragraph 2 because it contrasts the slow communication of the past with the fast communication of today. This shows a clear cause and effect relationship.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects with Paragraph 3 because it gives a specific example of a method of communication that is fast. This is a broader to specific strategy.
• Pair 4 (Paragraph 4 → Paragraph 5): Paragraph 5 logically follows Paragraph 4 because it explains why email is a fast method. It summarizes the importance of email in communication.