A.I. Explanation:

First sentence: Why this is the first line? This paragraph is the first sentence because it introduces the main topic of Churchill being a place that is easy to reach. It gives a broad overview of the location and its accessibility. This follows the rule of Introduction. Why other lines are not chosen? The other paragraphs are not chosen because they do not stand alone. For example, Paragraph 2 starts with 'Churchill' which assumes prior knowledge. Paragraph 3 starts with 'Despite' which is a conjunction. Paragraph 4 uses 'the' which assumes prior knowledge of 'the town'. Paragraph 5 starts with 'Tours' which needs context from earlier sentences.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it summarizes the main point about the popularity of tours in Churchill. It brings together the earlier points about eco-tourism and the attractions of the town.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects to Paragraph 1 because it continues the topic of Churchill. It uses the Connector strategy with 'but' to show a contrast between being a port and the rise of eco-tourism.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects to Paragraph 2 because it shows the result of eco-tourism. It uses the Cause and Effect Relationship strategy, as more visitors come because of eco-tourism.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects to Paragraph 3 because it explains why visitors come. It uses the Broader to Specific Strategy, as it gives specific reasons for the attraction of polar bears.
• Pair 4 (Paragraph 4 → Paragraph 5): Paragraph 5 connects to Paragraph 4 because it gives more detail about the attraction of the bears. It uses the Logical Order strategy, as it follows the explanation of why Churchill is important with the specific tours that people take.