46. What is the main idea of this passage? (A) Retailers tend to spend a lot of money doing research on the layout of the stores. (B) Retailers use a lot of measures based on physical and psychological studies to increase their profit. (C) Shoppers must be careful when they decide to buy anything with a price tag which ends with a 9. (D) Retailers know that consumers will pay much more attention to the dollars than the cents.