A.I. Explanation:

First sentence: Why this is the first line? This paragraph is the first line because it introduces the main topic. It gives a broad overview of how goods were moved in the past. It does not refer to any previous information. Why other lines are not choosen? Paragraph 2 starts with "This situation" which refers back to the previous context, so it is not independent. Paragraph 3 starts with "While" which is a conjunction, making it not independent. Paragraph 4 starts with "The shipping system" which uses the definite article "the" and assumes prior knowledge, so it is not independent. Paragraph 5 starts with "It was also necessary" which uses a pronoun, making it not independent.

Concluding sentence: Why this is the last line? This paragraph is the last line because it wraps up the discussion about the changes needed for the shipping system. It provides a final point about the investments required, which concludes the overall theme.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects with Paragraph 1 because it explains the problems that happened due to the situation described in Paragraph 1. This shows a cause and effect relationship.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects with Paragraph 2 because it talks about the benefits of the invention mentioned in Paragraph 2. It shows a logical order from problems to benefits.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects with Paragraph 3 because it explains the changes needed after the invention. This shows a broader to specific strategy, moving from general benefits to specific changes.
• Pair 4 (Paragraph 4 → Paragraph 5): Paragraph 5 connects with Paragraph 4 because it continues to explain the needs for building new infrastructure. This shows a logical order of requirements.