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 clear definition of what a memoir is. This follows the rule of Topic Sentence. It does not refer to any previous information, so it stands alone. Why other lines are not chosen? The other paragraphs are not chosen because they do not meet the criteria for being independent. For example, Paragraph 2 starts with 'In many ways,' which is a conjunction. Paragraph 3 starts with 'However,' which is also a conjunction. Paragraph 4 uses 'A memoir' but it refers back to the concept of memoirs, which is not independent.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it summarizes the main points about memoirs and autobiographies. It gives a clear conclusion about the differences between the two. This follows the rule of Summary Style.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects to Paragraph 1 because it continues the idea of memoirs. It uses the Connector 'In many ways' to show that it is related to the previous statement.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects to Paragraph 2 because it explains the difference between memoirs and autobiographies. The word 'However' shows a contrast, which links the two ideas.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects to Paragraph 3 because it explains the key difference mentioned in the previous paragraph. It follows the Logical Order as it gives more detail about the difference.