A.I. Explanation:

First sentence: Why this is the first line? This paragraph is the first sentence because it introduces the main topic about humans and their skin. It does not need other sentences to understand it. It does not start with a conjunction or a pronoun. It talks about a general idea without referring to previous information. Why other lines are not chosen? The other paragraphs are not chosen because they do not meet the rules for being independent. For example, Paragraph 2 starts with 'Humans evolved' which is not general. Paragraph 3 starts with 'Humans also have' which refers back to humans. Paragraph 4 starts with 'To make these glands' which is not a general statement. Paragraph 5 starts with 'This enabled them' which refers back to previous ideas.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it wraps up the main ideas. It shows the result of the previous points about human evolution and adaptation. It uses the 'Conclusive Words' rule because it summarizes how these changes helped humans.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects with Paragraph 1 because it explains why humans have naked skin. It uses the 'Broader to Specific Strategy' because it starts with a general idea about humans and then gives a specific reason for their skin.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects with Paragraph 2 because it gives more details about how humans adapted. It uses the 'Logical Order' rule because it continues the idea of human evolution by explaining a specific feature.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects with Paragraph 3 because it explains what humans did to improve their sweat glands. It uses the 'Cause and Effect Relationship' rule because losing hair helps the glands work better.
• Pair 4 (Paragraph 4 → Paragraph 5): Paragraph 5 connects with Paragraph 4 because it explains the result of losing hair. It uses the 'Cause and Effect Relationship' rule because losing hair helps humans get food and stay cool.