A.I. Explanation:

First sentence: Why this is the first line? This paragraph is the first sentence because it introduces the main topic of making macarons. It gives a broad overview of what is needed to start the process. It does not use any pronouns or definite articles that refer to previous information. Why other lines are not chosen? Paragraph 2 starts with "After aging" which is a reference to a previous action, so it cannot be first. Paragraph 3 starts with "The dry ingredients" which uses the definite article "the" and assumes prior knowledge. Paragraph 4 starts with "Once filled" which also refers to a previous step, making it not independent.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it wraps up the process of making macarons. It gives the final step and shows the result of all the previous actions.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects with Paragraph 1 because it continues the process of making macarons. It uses the connector "After aging" to show the next step after the preparation mentioned in Paragraph 1.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 logically follows Paragraph 2 because it describes what happens after whisking the egg whites. It shows a logical order of steps in making macarons.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects with Paragraph 3 because it describes what happens after the dry ingredients are added. It shows the next step in the process of making macarons.