A.I. Explanation:

First sentence: Why this is the first line? This paragraph is the first sentence because it introduces the main topic of art history. It clearly states what art history is about. This follows the rule of Topic Sentence. Why other lines are not chosen? The other paragraphs are not chosen because they do not stand alone as the first sentence. For example, Paragraph 2 starts with 'The study' which needs context. Paragraph 3 starts with 'Art historians' which refers to a group and needs prior information. Paragraph 4 starts with 'Art history' but does not introduce the topic. Paragraph 5 starts with 'So' which is a conjunction and cannot be first.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it wraps up the discussion about art history. It gives a summary of what art history means and how it is used. This follows the Conclusive Words rule.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects with Paragraph 1 because it gives examples of what is included in the study of art history. This follows the Broader to Specific Strategy.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects with Paragraph 2 because it continues to explain what art history does. It shows how art history helps us understand different cultures. This follows the Logical Order rule.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects with Paragraph 3 because it explains what art historians do. It shows how they look at different times in art history. This follows the Topic Example rule.
• Pair 4 (Paragraph 4 → Paragraph 5): Paragraph 5 connects with Paragraph 4 because it explains the term 'art history' and how it is used. This follows the Connector Strategy.