Final answer:
Costco, known for selling a variety of items like groceries, mattresses, and computers, is categorized as a Warehouse Club because it offers bulk merchandise at discounted prices for members. The correct option is A.
Step-by-step explanation:
The major type of retail operations that best classifies Costco, which sells groceries, mattresses, and computers, is a Warehouse Club. This type of retail operation refers to a retail store, often in a warehouse-like environment, where customers can buy a variety of bulk merchandise at discounted prices. Unlike supermarkets that specialize mainly in food products and require no membership, a Warehouse Club like Costco requires membership and offers a wide range of products including groceries, home goods, electronics, and more. Specialty stores focus on a specific category of goods, which does not match Costco's wide product range. Department stores also offer a broad assortment of goods, but they are more like traditional retail stores with distinct departments and do not typically offer goods in bulk like Warehouse Clubs.