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 about the census in Britain. It does not need any other sentence for context. It is a general statement about how often the census happens in Britain. 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 'The earliest census counts...' which refers to previous information. Paragraph 3 starts with 'In Britain a census...' but it is not general enough to stand alone. Paragraph 4 uses 'Censuses have been carried out...' which also assumes prior knowledge. Paragraph 5 starts with 'The population...' which is too specific and does not introduce the topic.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it wraps up the main ideas of the text. It summarizes how the census data can help understand population changes. It uses conclusive language by explaining the outcome of the census.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects with Paragraph 1 because it gives more detail about what happens during the census in Britain. This follows the Broader to Specific Strategy, as the first sentence talks about the census in general, and the second sentence explains what each household does.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects with Paragraph 2 because it shifts the focus to the history of census counts. This shows a Logical Order, as it moves from the current practice in Britain to the historical context of census counts.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects with Paragraph 3 because it continues the discussion about census history. This follows the Logical Order strategy, as it moves from the earliest counts in China to the specific years when censuses started in the USA and Britain.
• Pair 4 (Paragraph 4 → Paragraph 5): Paragraph 5 connects with Paragraph 4 because it discusses how to understand population changes between censuses. This follows the Cause and Effect Relationship strategy, as it explains the result of having census data.