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 debate about the number of oceans. It does not need another sentence for context. It sets up the discussion without going into details. This follows the rule of Topic Sentence. Why other lines are not chosen? Paragraph 2 starts with "Some consider" which is not independent because it refers back to the debate. Paragraph 3 starts with "Now, those that side" which is also not independent as it assumes prior knowledge. Paragraph 4 starts with "The IHO has settled" which uses the definite article "the" and assumes knowledge of the IHO.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it concludes the discussion. It wraps up the information by stating the resolution of the debate. This follows the rule of Conclusive Words.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects to Paragraph 1 because it continues the discussion about the number of oceans. It provides a specific view on the debate mentioned in Paragraph 1. This follows the Logical Order rule.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 logically follows Paragraph 2 because it introduces the idea of a fifth ocean. It shows a shift in the debate from four oceans to five. This follows the Broader to Specific Strategy.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects to Paragraph 3 because it explains how the debate is settled. It provides the action taken by the IHO regarding the fifth ocean. This follows the Cause and Effect Relationship rule.