In the current notebook computer market, there are a large number of cheap "parallel imports" that enter the market through informal channels, that is, products that are not allowed to be sold in mainland China in accordance with manufacturer policies. A large number of "parallel imports" have impacted the sales of products informal channels. Analysts believe that the main reason for this phenomenon is that the price advantage of parallel imports is too large. Which of the following is a prerequisite that this analyst must imply in his analysis? ['Market supervision departments have not cracked down on parallel imports.', 'Many consumers cannot afford the prices of formal channel products.', "The manufacturer's sales policy is unreasonable, leaving room for parallel imports.", 'Compared with products from regular channels, "parallel imports" are more cost-effective.']