A.I. Explanation:

First sentence: Why this is the first line? This paragraph is the first sentence because it introduces the main topic about the value of amber. It does not need any other sentence for context. It is a general statement about the Romans and their use of amber. Why other lines are not chosen? The other paragraphs are not chosen because they do not stand alone. For example, 'They also believed...' starts with a pronoun and needs the previous sentence for context. 'Furthermore, the Greeks found...' uses a connector and refers back to earlier ideas. 'They called this phenomenon...' also uses a pronoun and needs prior information.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it wraps up the discussion about amber. It gives a final detail about the term 'electron' and connects back to the main topic of amber.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects with Paragraph 1 because it continues the idea about amber. The phrase 'They also believed' shows that it adds more information about the Romans' beliefs.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects with Paragraph 2 because it introduces a new idea about the Greeks. The word 'Furthermore' shows that it adds more information about amber, linking the two ideas.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects with Paragraph 3 because it explains what the Greeks called the phenomenon. The phrase 'They called this phenomenon' shows a direct link to the previous idea about amber.