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 gives a broad overview of the Pyramids of Giza and their importance. This follows the rule of Topic Sentence. Why other lines are not chosen? Paragraph 2 starts with "Built as tombs..." which is not independent because it uses a definite article "the". Paragraph 3 starts with "However..." which is a conjunction and cannot stand alone. Paragraph 4 starts with "Some theories..." which is not general enough to be the first sentence.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it provides a theory about the construction of the Pyramids. It wraps up the discussion by giving a possible explanation, which follows the Conclusive Words rule.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects to Paragraph 1 because it gives more specific information about the Pyramids. This follows the Broader to Specific Strategy.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects to Paragraph 2 because it discusses the mystery of the construction techniques. This follows the Logical Order rule.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects to Paragraph 3 because it presents theories about how the Pyramids were built. This follows the Cause and Effect Relationship rule.