A.I. Explanation:

First sentence: Why this is the first line? This paragraph is the first sentence because it introduces the main topic of fruits and their importance in a diet. It does not refer to any previous information and gives a broad overview of the subject. This follows the rule of Topic Sentence. Why other lines are not chosen? The other paragraphs are not chosen because they do not meet the criteria for being independent. For example, Paragraph 2 starts with 'They', which is a pronoun and needs context. Paragraph 3 starts with 'Additionally', which is a conjunction. Paragraph 4 starts with 'Nevertheless', which is also a conjunction. All these reasons make them not independent.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it wraps up the discussion about fruits. It gives a final point about moderation, which reflects the overall theme of the importance of fruits in a diet.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects with Paragraph 1 because it continues the idea of fruits being important. The phrase 'They provide' refers back to 'Fruits', showing a clear link. This follows the Noun Pronoun Rule.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects with Paragraph 2 because it adds more information about fruits. The word 'Additionally' shows that it is giving more details about the benefits of fruits. This follows the Connector Strategy.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects with Paragraph 3 because it introduces a contrasting idea. The word 'Nevertheless' shows that it is talking about a different aspect of fruits. This follows the Contrast rule.