A.I. Explanation:

First sentence: Why this is the first line? This paragraph is the first sentence because it introduces the main topic of the text, which is Namibia. It gives a broad overview of the country without going into details. This follows the rule of Topic Sentence. Why other lines are not chosen? The other paragraphs are not chosen because they do not stand alone. For example, 'One of the world's driest areas...' starts with a specific detail and needs context. 'For its size, Namibia has few people...' also needs context about Namibia. 'But the most valuable products...' refers to products without introducing them first. 'White people make up ten per cent...' talks about a specific group without introducing Namibia.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it wraps up the discussion about Namibia's population and their control over industries. It provides a conclusion to the information presented in the previous paragraphs.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects with Paragraph 1 because it continues to describe Namibia. This follows the Logical Order rule, as it gives more information about the geography of Namibia.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects with Paragraph 2 because it talks about the people living in Namibia after describing its geography. This follows the Broader to Specific Strategy, as it moves from the general area to specific details about the population.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects with Paragraph 3 because it shifts from talking about the population to discussing the valuable products of Namibia. This follows the Logical Order rule, as it presents a new aspect of Namibia's economy.
• Pair 4 (Paragraph 4 → Paragraph 5): Paragraph 5 connects with Paragraph 4 because it discusses the control of industries related to the valuable products mentioned. This follows the Cause and Effect Relationship rule, as it shows how the population relates to the economy.