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 quantum theory. It gives a broad overview of what quantum theory is about without going into details. This follows the rule of Topic Sentence. Why other lines are not choosen? The other paragraphs are not chosen because they do not stand alone. For example, Paragraph 2 starts with "Initially," which is a conjunction. Paragraph 3 starts with "However," which is also a conjunction. Paragraph 4 uses "As a result," which shows it is not independent. Therefore, they cannot be the first sentence.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it summarizes the impact of quantum theory. It wraps up the discussion by showing the results of the theory, which follows the rule of Conclusive Words.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects with Paragraph 1 because it continues the discussion about quantum theory. It shows the initial reaction to this theory, which is a logical order of ideas.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects with Paragraph 2 because it explains how the skepticism changed over time. The word "However" shows a contrast between the skepticism and the acceptance of quantum theory.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects with Paragraph 3 because it shows the results of accepting quantum theory. The phrase "As a result" indicates that the advancements are a consequence of the acceptance of quantum theory.