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. It gives a broad overview of the experiment and its focus on human behaviour and morality. This is a general statement that does not need other sentences for context. It does not start with a conjunction or use pronouns that refer to previous ideas. 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 researchers" which refers back to the researchers mentioned in the first paragraph. Paragraph 3 starts with "However," which is a conjunction. Paragraph 4 starts with "Similarly," which is also a conjunction. Paragraph 5 starts with "It seems fairly clear" which uses a pronoun "It" that refers back to the previous ideas.

Concluding sentence: Why this is the last line? This paragraph is the last line because it summarizes the main idea of the text. It wraps up the discussion about how the environment affects moral decisions. It uses a conclusive style to bring together the earlier points.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): This pair connects because Paragraph 2 gives an example of the experiment mentioned in Paragraph 1. It follows the Broader to Specific Strategy, where the first paragraph introduces the topic and the second paragraph provides specific details about the experiment.
• Pair 2 (Paragraph 2 → Paragraph 3): This pair connects because Paragraph 3 shows a different result from the same experiment in Paragraph 2. The word "However" indicates a contrast, which links the two ideas. This follows the Contrast rule.
• Pair 3 (Paragraph 3 → Paragraph 4): This pair connects because Paragraph 4 gives another example of how the environment affects behaviour, just like Paragraph 3. The word "Similarly" shows that both paragraphs discuss similar ideas, following the Connector Strategy.
• Pair 4 (Paragraph 4 → Paragraph 5): This pair connects because Paragraph 5 summarizes the findings from Paragraph 4. It follows the Logical Order rule, where the conclusion follows the examples given.