A.I. Explanation:

First sentence: Why this is the first line? This paragraph is the first sentence because it introduces the main topic of the text. It tells us about the two types of sugar. This is a broad overview of the subject. It does not need any other sentence to understand it. Why other lines are not chosen? The other paragraphs are not chosen because they do not stand alone. For example, Paragraph 2 starts with "The cane" which is a pronoun and needs more context. Paragraph 3 starts with "Sugar beet" but it is specific and does not introduce the topic. Paragraph 4 starts with "Although" which is a conjunction and shows a contrast, so it cannot be first.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it wraps up the discussion about sugar. It gives a conclusion about how both types of sugar taste the same, even if they look different. This is a summary style that brings together the earlier points.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects with Paragraph 1 because it continues the topic of sugar. It uses the logical order rule. The first paragraph introduces the types of sugar, and the second paragraph explains one type, cane.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects with Paragraph 2 because it contrasts with it. It uses the contrast rule. The second paragraph talks about cane needing hot climates, while the third talks about beet growing in cooler climates.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects with Paragraph 3 because it discusses both types of sugar. It uses the topical order rule. The third paragraph talks about sugar beet, and the fourth paragraph mentions both cane and beet.