A.I. Explanation:

First sentence: Why this is the first line? This paragraph is the first line because it introduces the main topic of the text, which is the need for fresh water. It is a general statement that does not refer to any previous information. This follows the rule of Topic Sentence. Why other lines are not chosen? Paragraph 2 starts with 'Without water,' which is a dependent phrase. Paragraph 3 starts with 'Although,' which is a conjunction. Paragraph 4 starts with 'Of the total supply,' which is specific and does not introduce the main topic.

Concluding sentence: Why this is the last line? This paragraph is the last line because it summarizes the information about fresh water. It provides important facts that wrap up the discussion about the need for fresh water. This follows the rule of Summary Style.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects with Paragraph 1 because it explains why fresh water is important. It uses the Connector strategy, showing a cause and effect relationship.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects with Paragraph 2 because it gives more detail about the need for fresh water. It follows the Broader to Specific Strategy, explaining the general need for water and then focusing on humans.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects with Paragraph 3 because it provides information about the availability of fresh water. It uses the Logical Order strategy, moving from the need for fresh water to the facts about its supply.