A.I. Explanation:

First sentence: Why this is the first line? This paragraph is the first sentence because it is a general statement about food. It introduces the main topic of the text, which is about plants and food. It does not need another sentence for context. Why other lines are not chosen? The other paragraphs are not chosen because they do not meet the criteria for being independent. For example, Paragraph 2 starts with 'It', which is a pronoun and needs context. Paragraph 3 uses 'Plants' but does not introduce the topic. Paragraph 4 starts with 'Chlorophyll', which is specific and assumes prior knowledge. Paragraph 5 starts with 'It', which is also a pronoun.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it wraps up the explanation of how plants make food. It gives the final detail about the process, showing the importance of sunlight. This is a clear conclusion to the topic.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects to Paragraph 1 because it gives an example of how food is related to plants. It explains that even animals depend on plants for energy. This shows a logical order from a general statement to a specific example.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 follows Paragraph 2 because it explains how plants make food. It gives more detail about the process mentioned in the previous paragraph. This shows a logical order from an example of animals to how plants create food.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects to Paragraph 3 because it explains how chlorophyll works in plants. It gives specific details about the process of making food. This shows a logical order from a general statement about plants to specific information about chlorophyll.
• Pair 4 (Paragraph 4 → Paragraph 5): Paragraph 5 follows Paragraph 4 because it explains how chlorophyll works with sunlight. It shows the process of making food in plants. This is a logical order from the action of chlorophyll to the energy needed for that action.