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 and its definition. It uses the rule of Topic Sentence because it gives a clear idea about what the text will discuss. It does not need any other sentence for context. Why other lines are not chosen? The other paragraphs are not chosen because they do not stand alone. For example, Paragraph 2 starts with 'For this reason,' which is a conjunction. Paragraph 3 starts with 'Until,' which is also a conjunction. Paragraph 4 starts with 'Today,' which does not introduce a new idea. They all need more context to make sense.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it wraps up the discussion about art. It uses the rule of Conclusive Words because it shows a change in the value of art today. It summarizes the main idea that art is valued differently now.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects to Paragraph 1 because it explains the idea of 'mimesis' further. It uses the rule of Broader to Specific Strategy. The first sentence gives a general idea about art, and the second sentence gives more detail about its meaning.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects to Paragraph 2 because it talks about how art was valued in the past. It uses the rule of Logical Order. The second sentence explains the meaning of art, and the third sentence shows how this meaning was applied historically.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects to Paragraph 3 because it shows a change in how art is valued. It uses the rule of Cause and Effect Relationship. The third sentence explains the past value of art, and the fourth sentence shows that this has changed.