A.I. Explanation:

First sentence: Why this is the first line? This paragraph is the first sentence because it introduces the main idea about staff happiness and job security. It does not refer to any previous information. It sets the stage for the topic without going into details. Why other lines are not chosen? Paragraph 2 starts with 'However,' which is a conjunction. This means it cannot stand alone. Paragraph 3 starts with 'People,' but it refers to a specific group without introducing the topic first. Paragraph 4 starts with 'If,' which also makes it dependent on another idea.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it wraps up the ideas presented. It shows the result of not having promotion opportunities, which is demotivation. It concludes the discussion on employee satisfaction.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects with Paragraph 1 using the 'Connector' strategy. The word 'However' shows a contrast to the idea in Paragraph 1. It explains that not all employees are happy with simple jobs.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 follows Paragraph 2 logically. It uses the 'Logical Order' strategy. It continues the idea of employee satisfaction by explaining that people want promotions to feel fulfilled.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects with Paragraph 3 using the 'Cause and Effect Relationship' strategy. It shows that without promotion opportunities, employees will feel demotivated.