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 text. It gives a clear definition of what a joint venture (JV) is. This follows the rule of Topic Sentence. It does not need any other sentence for context. Why other lines are not chosen? The other paragraphs do not qualify as the first sentence. For example, Paragraph 2 starts with 'This task', which uses a pronoun and needs context. Paragraph 3 starts with 'In a JV', which also needs prior information. Paragraph 4 starts with 'However', which is a conjunction and shows a continuation of thought.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it wraps up the main ideas about a joint venture. It gives a final thought about how the JV is separate from other business interests. This follows the Conclusive Words rule.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects with Paragraph 1 because it gives examples of what the task can be. This follows the Broader to Specific Strategy. The first sentence talks about a joint venture, and the second sentence explains what tasks can be in a JV.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects with Paragraph 2 because it explains the responsibilities of participants in a JV. This follows the Logical Order rule. The second sentence talks about tasks, and the third sentence explains what happens in a JV.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects with Paragraph 3 because it adds more information about the JV. This follows the Cause and Effect Relationship rule. The third sentence talks about responsibilities, and the fourth sentence explains how the JV is separate from other interests.