A.I. Explanation:

First sentence: Why this is the first line? This paragraph is the first sentence because it introduces the main topic of digital photography. It gives a broad overview of how understanding photography can improve pictures. It does not use any pronouns or definite articles that need prior context. Why other lines are not chosen? Paragraph 2 starts with "The first step" which needs context, so it is not independent. Paragraph 3 starts with "For example" which also needs context. Paragraph 4 starts with "Finally" which shows it is not independent as it refers to previous ideas.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it wraps up the ideas by talking about the importance of practice. It uses the word "Finally" which signals the end of the discussion.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects to Paragraph 1 because it gives the first step after understanding the basics. This shows a logical order from general knowledge to specific action.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects to Paragraph 2 because it gives an example of how to use the manual settings. This shows a broader to specific strategy, where the example follows the first step.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects to Paragraph 3 because it talks about practising the techniques mentioned in Paragraph 3. This shows a logical order from example to practice.