A.I. Explanation:

First sentence: Why this is the first line? This paragraph is the first line because it introduces the main topic of food advertising. It gives a broad overview of the subject without going into details. It does not use any pronouns or definite articles that would need prior context. Why other lines are not chosen? Paragraph 2 starts with 'Food product' which is not independent because it refers back to the topic. Paragraph 3 starts with 'In other media' which is not independent because it assumes knowledge of previous information. Paragraph 4 starts with 'Food manufactures' which is not independent because it refers to a specific group without prior context.

Concluding sentence: Why this is the last line? This paragraph is the last line because it wraps up the discussion about food advertising. It provides a final statement about the overall spending in the food industry, which reflects the overarching theme of the text.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects with Paragraph 1 because it provides specific details about the expenditures in food advertising. This follows the Broader to Specific Strategy, where the first paragraph gives a general statement and the second paragraph gives specific examples.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 logically follows Paragraph 2 because it continues to discuss food advertising but in different media. This shows a Logical Order as it expands on the topic introduced in the previous paragraph.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects with Paragraph 3 because it summarizes the overall spending on food advertising. This follows the Topic Example Strategy, where the last paragraph gives a conclusion about the advertising spending.