Final answer:
The competitive relationship between Arby's and Panda Express is a monopolistic competition.
Step-by-step explanation:
The competitive relationship between Arby's and Panda Express in this situation is called 'monopolistic competition'.
In monopolistic competition, there are many sellers offering differentiated products. Each seller has some control over the price they charge, and they compete for customers based on factors like product quality, location, and customer service.
In this case, Arby's and Panda Express are both fast food restaurants, but they offer different types of cuisine. The customer's decision depends on their preferences for roast beef sandwiches or Chinese food. While Arby's and Panda Express are competitors, they are not direct substitutes for each other, as they offer distinct products.