First sentence: Why this is the first line? This paragraph is the first line because it introduces the main topic of the text. It talks about the beginning of animal domestication, which is a broad overview of the subject. It does not use any specific details or references to previous information. 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 "Initially," which is a transitional word. Paragraph 3 uses "Over time," which also indicates a continuation. Paragraph 4 starts with "Consequently," which shows a connection to previous ideas. Therefore, they cannot be the first sentence.

Concluding sentence: Why this is the last line? This paragraph is the last line because it wraps up the ideas presented in the text. It uses the word "Consequently," which indicates a conclusion. It summarizes how the relationship has developed over time.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects with Paragraph 1 because it continues the idea of animal domestication. It explains how animals were used at the start. This shows a logical order from the general idea of domestication to a specific use of animals.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects with Paragraph 2 because it shows how the roles of animals changed. It follows the idea of initial uses and then explains how these roles expanded. This is a broader to specific strategy.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects with Paragraph 3 because it shows the result of the changing roles of animals. It explains how these changes have affected the relationship between humans and animals. This is a cause and effect relationship.