A.I. Explanation:

First sentence: Why this is the first line? This paragraph is the first sentence because it introduces the main idea of the text. It uses the rule of Topic Sentence because it gives a broad overview of the subject. It tells us that history is not complete and sets the stage for the following sentences. Why other lines are not chosen? The other paragraphs are not chosen because they do not stand alone. For example, Paragraph 2 starts with 'They', which is a pronoun and needs context. Paragraph 3 talks about what history books tell us, but it does not introduce the main idea. Paragraph 4 is too specific and talks about teaching history, which is not the main topic.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it wraps up the main idea of the text. It uses the rule of Summary Style because it brings together the earlier points about selectivity and choices in history.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects to Paragraph 1 because it explains what is meant by 'selective'. It uses the Logical Order rule because it continues the idea of selectivity in history.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 follows Paragraph 2 because it talks about the need for choices in history. It uses the Cause and Effect Relationship rule because it shows that because history is selective, choices must be made.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects to Paragraph 3 because it gives an example of the choices that need to be made. It uses the Broader to Specific Strategy because it takes the general idea of making choices and applies it to teaching history.