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 review of antidepressants. It does not refer to any previous information and gives a broad overview of the findings. 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 'The true effectiveness,' which uses 'the' and assumes prior knowledge. Paragraph 3 starts with 'The study authors recommend,' which also uses 'the.' Paragraph 4 starts with 'This was widely opposed,' which uses 'this' and refers back to something not mentioned yet. Paragraph 5 starts with 'It is therefore recommended,' which uses 'it' and assumes prior context.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it gives a final recommendation based on the previous discussions. It wraps up the topic by suggesting a way to approach the use of antidepressants. This follows the Summary Style rule, as it brings together the earlier points.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects to Paragraph 1 because it continues the discussion about the effectiveness of antidepressants. This follows the Logical Order rule, as it provides more details about the findings mentioned in Paragraph 1.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects to Paragraph 2 because it gives a recommendation based on the findings discussed in Paragraph 2. This follows the Cause and Effect Relationship rule, as the recommendation is a result of the unclear effectiveness and risks mentioned before.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects to Paragraph 3 because it explains the opposition to the recommendations made in Paragraph 3. This follows the Contrast rule, as it shows a different perspective on the recommendations.
• Pair 4 (Paragraph 4 → Paragraph 5): Paragraph 5 connects to Paragraph 4 because it provides a new recommendation after discussing the opposition. This follows the Logical Order rule, as it shows a progression from the opposition to a new suggestion.