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, which is Diwali. It gives a broad overview of the festival without going into details. It does not use any pronouns or definite articles that would need prior context. Why other lines are not chosen? Paragraph 2 starts with "The festival" which uses a definite article and assumes prior knowledge. Paragraph 3 starts with "Families" which is a pronoun referring back to the festival. Paragraph 4 starts with "In addition" which is a transitional phrase and does not stand alone.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it summarizes the overall theme of the festival. It wraps up the discussion by highlighting the cultural significance and activities of Diwali.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects to Paragraph 1 because it continues the topic of Diwali. It gives more details about the festival's duration and customs. This shows a logical order from a general statement to specific information.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects to Paragraph 2 because it describes what families do during the festival. This shows a logical order where the specific customs follow the mention of the festival's duration.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects to Paragraph 3 because it adds more information about the festival's significance. It shows a logical order where the cultural aspects follow the actions of families during the festival.