A.I. Explanation:

First sentence: Why this is the first line? This paragraph is the first sentence because it introduces the main topic of communication in daily life. It gives a broad overview of how people share information. It does not refer to any previous ideas or use specific terms that need context. Why other lines are not chosen? Paragraph 2 starts with 'When this exchange occurs', which needs context from a previous sentence. Paragraph 3 starts with 'The sender or source', which assumes prior knowledge of the topic. Paragraph 4 starts with 'Once the message has been', which also needs context. All these sentences do not stand alone.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it wraps up the discussion about communication. It shows the result of the communication process, which is feedback. It summarizes the main points made in the previous paragraphs.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects with Paragraph 1 because it explains what happens when exchanges occur. It uses the logical order of ideas, moving from general exchanges to the specific term 'communication process'.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 follows Paragraph 2 because it describes the basic elements of the communication process. It uses the broader to specific strategy, moving from the concept of communication to its key parts.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects with Paragraph 3 because it explains what happens after the elements of communication are in place. It shows a logical order from the elements to the feedback process.