First sentence: Why this is the first line? This paragraph is the first line because it introduces the main topic of the text. It talks about flowers and their role in the ecosystem. This is a general statement that does not need other sentences for context. It does not start with a conjunction or use pronouns. Why other lines are not chosen? Paragraph 2 starts with 'This process', which uses a pronoun and needs context. Paragraph 3 starts with 'Consequently', which is a conjunction. Paragraph 4 starts with 'Therefore', which is also a conjunction. All these reasons make them not independent.

Concluding sentence: Why this is the last line? This paragraph is the last line because it wraps up the main ideas. It gives a solution to the problems discussed in the earlier paragraphs. The word 'Therefore' shows that this is a conclusion based on the previous information.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects to Paragraph 1 because it explains why flowers are important. The phrase 'This process' refers back to the role of flowers in attracting pollinators. This shows a clear flow of ideas.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects to Paragraph 2 because it shows the effect of the decline of pollinators. The word 'Consequently' shows that the decline is a result of the importance of pollinators mentioned in Paragraph 2.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects to Paragraph 3 because it gives a solution to the problem of pollinator decline. The word 'Therefore' shows that protecting flowers is important because of the threat mentioned in Paragraph 3.