A.I. Explanation:

First sentence: Why this is the first line? This paragraph is the first sentence because it introduces the topic of cash transactions. It gives a clear idea about privacy and anonymity. This is a general statement that does not need other sentences for context. It does not start with a conjunction or use pronouns. Why other lines are not chosen? Paragraph 2 starts with 'Moreover,' which is a conjunction. Paragraph 3 starts with 'The whole structure,' which uses 'the' and assumes prior knowledge. Paragraph 4 starts with 'Electronic transactions,' which uses 'the' and assumes prior knowledge. Paragraph 5 starts with 'To support e-commerce,' which is not independent because it refers to a specific topic.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it wraps up the discussion. It gives a clear conclusion about what is needed for e-commerce, which is the main topic of the text.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects with Paragraph 1 because it adds more information about money. The word 'Moreover' shows that it continues the idea of money and its value.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects with Paragraph 2 because it explains why money is accepted. It talks about the structure of money and how it is based on faith, which follows the idea of value.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects with Paragraph 3 because it talks about electronic money. It shows how electronic transactions are part of the money system, following the discussion of traditional money.
• Pair 4 (Paragraph 4 → Paragraph 5): Paragraph 5 connects with Paragraph 4 because it talks about what is needed for e-commerce. It follows the idea of electronic transactions and explains the need for systems to support them.