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 in Western culture. It gives a broad overview of how art was defined over many centuries. It does not use any words that need prior context, making it clear and independent. Why other lines are not chosen? Paragraph 2 starts with "This meant" which needs context from the first sentence. Paragraph 3 starts with "During the Romantic period" which refers to a specific time and needs prior information. Paragraph 4 starts with "The Avant-garde art movement" which also assumes knowledge of art history.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it concludes the discussion about art movements. It provides a specific example of a movement that follows the earlier ideas, wrapping up the topic.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects to Paragraph 1 because it explains what the definition of art meant for artists. This shows a logical order where the definition leads to the actions of artists.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects to Paragraph 2 because it shows a change in how art was viewed. The actions of artists in Paragraph 2 lead to a new understanding of art in Paragraph 3, showing a logical order.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects to Paragraph 3 because it continues the discussion of art movements. The change in art during the Romantic period leads to the Avant-garde movement, showing a logical order.