A.I. Explanation:

First sentence: Why this is the first line? This paragraph is the first sentence because it introduces the main topic of angel investors. It gives a broad overview of who they are and why they invest. It does not refer to any previous information, making it independent. Why other lines are not chosen? Paragraph 2 starts with "These include," which means it needs more context. Paragraph 3 starts with "Thus," which shows it is connected to something before it. Paragraph 4 starts with "Because," which also shows it needs prior information. Paragraph 5 starts with "At these events," which refers to earlier ideas, so it is not independent.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it wraps up the discussion about how private companies meet angel investors. It provides a clear example of the meetings, which concludes the overall theme of the text.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects to Paragraph 1 because it explains the reasons why angel investors are interested in investing. This follows the Broader to Specific Strategy, where the first paragraph gives a general idea and the second paragraph provides specific reasons.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects to Paragraph 2 because it continues to explain what angel investors can offer. The word "Thus" shows a logical connection, indicating that the advice and contacts are part of the reasons mentioned before.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects to Paragraph 3 because it explains how private companies interact with angel investors. The word "Because" shows a cause-and-effect relationship, explaining why private companies need to meet angel investors.
• Pair 4 (Paragraph 4 → Paragraph 5): Paragraph 5 connects to Paragraph 4 because it gives an example of how private companies meet angel investors. The phrase "At these events" shows a logical order, as it describes what happens at the meetings mentioned in the previous paragraph.