A.I. Explanation:

First sentence: Why this is the first line? This paragraph is the first line because it introduces the main topic, which is the population of Iraq. It is a general statement that does not need other sentences for context. It does not use any pronouns or definite articles that refer 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 'The' which is a definite article, so it assumes prior knowledge. Paragraph 3 uses 'which' and refers back to the population growth rate, making it dependent. Paragraph 4 starts with 'In 2004' which gives a specific time and context, so it cannot stand alone.

Concluding sentence: Why this is the last line? This paragraph is the last line because it provides specific data that summarizes the information about the population growth. It gives a clear conclusion about the rates in 2004, which wraps up the discussion about the population of Iraq.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects to Paragraph 1 because it continues the topic of population. The phrase 'The population growth rate' shows a logical order from the general statement about the population to a specific detail about its growth.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects to Paragraph 2 because it shows the result of the decline in the population growth rate. The word 'however' is a connector that shows a contrast between the decline and the recovery of the growth rate.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects to Paragraph 3 because it provides specific data about the population growth rate after the recovery mentioned in Paragraph 3. This shows a logical order from the recovery to the current statistics.