First sentence: Why this is the first line? This paragraph is the first sentence because it introduces the main idea about dogs and their attention to human speech. It does not need another sentence for context. It sets up the topic without going into details. Why other lines are not chosen? Paragraph 2 starts with "Researchers" which makes it dependent on prior context. Paragraph 3 starts with "They" which refers back to dogs, so it is not independent. Paragraph 4 starts with "The research team" which also needs prior information to understand.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it wraps up the discussion. It summarizes the findings and connects them to other studies. It uses conclusive words like "supported" to show that it is the end of the argument.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): This pair connects because Paragraph 2 gives more details about the research mentioned in Paragraph 1. It follows the Broader to Specific Strategy, where the first paragraph talks about dogs' attention and the second explains how they can tell speech from non-speech.
• Pair 2 (Paragraph 2 → Paragraph 3): This pair connects because Paragraph 3 continues the idea from Paragraph 2. It uses the Noun Pronoun Rule, where "They" refers back to the brains of the dogs mentioned in Paragraph 2, showing a logical flow of ideas.
• Pair 3 (Paragraph 3 → Paragraph 4): This pair connects because Paragraph 4 summarizes the findings from Paragraph 3. It uses the Logical Order strategy, where the conclusion about the research team’s findings follows the details about dogs' responses.