Final answer:
Option (a), Conventional retailers in the US range from grocery stores with various departments to modern department stores and malls demonstrating monopolistic competition with non-identical products from numerous competing firms.
Step-by-step explanation:
Conventional retailers in the US are diverse and designed to meet various consumer needs and preferences. Major grocery stores are organized into departments like dairy, meats, produce, and more, each offering a wide variety of products. Aisles in these stores are usually packed with hundreds or thousands of items, providing consumers with a diverse selection to satisfy their needs.
On the other hand, the modern department store offers an array of goods under one roof with fixed prices, which was a significant change from the earlier small, family-run shops. Department stores like Macy's and Le Bon Marché have become iconic, providing customers with a mix of necessity items and small luxuries. The advent of department stores marked a shift towards modern consumerism, and they continue to play a crucial role in the retail landscape.
Furthermore, the presence of monopolistic competition in retail is illustrated by venues like the Mall of America, where a variety of stores like Ann Taylor, Urban Outfitters, Banana Republic, and Victoria's Secret coexist. Although they might all sell clothing, each store offers distinct products, setting the stage for monopolistic competition where many firms compete with non-identical items.