For handling multiple pricing groups with specific discounts or prices for different customer groups, the optimal approach involves setting up separate customer groups for customers, employees, and vendors (Answer A). This setup allows the storefront to apply specific price books to each group accurately based on their designation. Furthermore, utilizing campaigns and multiple promotions tailored to each customer group (Answer C) facilitates targeted marketing efforts and pricing strategies effectively. These practices ensure that each group receives relevant pricing adjustments and promotional offers, thereby enhancing the shopping experience and managing financial transactions efficiently within Salesforce B2C Commerce.