First sentence: Why this is the first line? This paragraph is the first sentence because it introduces the main topic. It tells us who Dr Pitsiladis is and what he is trying to find out. This is a broad overview of the subject. Why other lines are not chosen? The other paragraphs do not work as the first sentence. For example, Paragraph 2 starts with 'He' which is a pronoun. This means it needs more context. Paragraph 3 also starts with 'From this', which shows it is based on something before it. Paragraph 4 starts with 'So', which is a conjunction. This means it connects to something else. Paragraph 5 does not introduce the topic but talks about what he tested.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it wraps up the findings of Dr Pitsiladis. It gives a final result of his tests and shows the outcome of his research.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects to Paragraph 1 because it shows what Dr Pitsiladis did first. It uses the connector 'He began', which shows the action he took after stating his goal.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 follows Paragraph 2 logically because it explains what he concluded after taking the DNA samples. The phrase 'From this' shows a cause and effect relationship.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects to Paragraph 3 because it shows what he did next after his conclusion. The word 'So' indicates a logical order of actions.
• Pair 4 (Paragraph 4 → Paragraph 5): Paragraph 5 follows Paragraph 4 because it continues to explain what he did after looking at the East African way of life. The phrase 'He tested those children' shows a logical order of actions.