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 process. It talks about the first step, which is to get permissions. This shows it is an introductory sentence. It does not refer to any previous information. Why other lines are not chosen? Paragraph 2 starts with "After securing permissions," which means it needs the first paragraph for context. Paragraph 3 starts with "Preparing for this extreme environment," which is specific and does not introduce the topic. Paragraph 4 starts with "Personal safety and environmental preservation," which is also specific and does not set up the main topic.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it wraps up the main ideas. It talks about safety and preservation, which are important points for the expedition. It gives a final thought on the topic.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 logically connects with Paragraph 1 because it uses the connector "After securing permissions." This shows that the second paragraph follows the first step of getting permissions.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects with Paragraph 2 because it continues the topic of preparation. It shows the next step after planning is to prepare for the environment.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects with Paragraph 3 because it talks about what happens after preparation. It focuses on safety and preservation, which are important for the expedition.