Step 1: Identify what the phrases communicate. "100% natural", "No added sugar", "No preservatives" are health-related claims, not instructions or a price breakdown. Step 2: Consider the effect on the reader. These claims target health-conscious buyers and are designed to make the product seem better than alternatives. Step 3: Match to the correct purpose. The writer uses positive health claims to encourage purchase — this is persuasion. Answer: to persuade buyers.