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. It uses a broad overview rule. It tells us that the sense of smell is important without going into details. Why other lines are not chosen? The other paragraphs are not chosen because they do not stand alone. For example, "Odours affect us on a physical..." starts with a specific idea and needs more context. The same goes for the other sentences.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it wraps up the main idea. It shows the conclusion about the importance of smell. It uses conclusive words by explaining what we learn when we lose our sense of smell.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects to Paragraph 1 because it explains how the sense of smell affects us. This is a logical order because it goes from a general statement to a specific effect.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects to Paragraph 2 because it talks about how we often do not notice these effects. This shows a logical flow from the effects of odours to our awareness of them.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects to Paragraph 3 because it explains what happens when we lose our sense of smell. This shows a cause and effect relationship, where losing the sense makes us aware of its importance.