A.I. Explanation:

First sentence: Why this is the first line? This paragraph is the first line because it introduces the main topic of the competition. It shows why the competition is important. It does not need another sentence for context. It does not start with a conjunction or use pronouns. It uses an indefinite article to introduce the idea of the competition. Why other lines are not chosen? Paragraph 2 starts with 'Another' which is a conjunction. Paragraph 3 starts with 'When' which is also a conjunction. Both of these cannot stand alone without context.

Concluding sentence: Why this is the last line? This paragraph is the last line because it wraps up the discussion by giving specific examples of questions. It shows the main theme of curiosity in science writing. It does not need more information after it.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects to Paragraph 1 because it uses the word 'Another'. This shows that it adds more reasons related to the importance of science writing. This is a Connector strategy.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects to Paragraph 2 because it gives examples of the questions people ask about science. This shows a Broader to Specific Strategy, where the general idea of science writing leads to specific questions.