A.I. Explanation:

First sentence: Why this is the first line? This paragraph is the first sentence because it introduces the main topic. It talks about humans and their similarities with other mammals. This is a general statement that sets the stage for the rest of the text. It does not use any specific details or references to other sentences. Why other lines are not chosen? The other paragraphs are not chosen because they do not meet the criteria for being independent. - Paragraph 2 starts with "The two other living primate species..." which uses a definite article "the" and refers to specific species. - Paragraph 3 starts with "We have spent..." which uses a pronoun "we" that refers back to humans. - Paragraph 4 starts with "However, as much like..." which is a transitional phrase and does not stand alone.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it wraps up the discussion. It summarizes the main point about similarities and differences. It uses the phrase "as much like..." which indicates a conclusion about the topic.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects with Paragraph 1 because it continues the discussion about humans. It gives specific examples of primate species that are similar to humans. This shows a logical order from a general statement about humans to specific examples.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects with Paragraph 2 because it talks about the phylogenetic tree, which relates to the chimpanzee and bonobo mentioned in Paragraph 2. This shows a logical order as it explains why we study these species.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects with Paragraph 3 because it discusses the differences between humans and the chimpanzee and bonobo. This shows a cause and effect relationship, where studying the phylogenetic tree leads to understanding both similarities and differences.