Final answer:
Blue cheese is a common choice for a buffalo chicken sandwich due to its ability to complement the spicy buffalo sauce, although mozzarella, cheddar, pepper jack, or American cheese may also be used.
Step-by-step explanation:
A buffalo chicken sandwich typically includes a type of cheese that balances out the spiciness of the buffalo sauce. While there is no single standard type of cheese for a buffalo chicken sandwich, some popular cheese choices include blue cheese, mozzarella, cheddar, pepper jack, or American cheese. Blue cheese is especially common because it pairs well with the bold flavors of buffalo sauce.
The cheese used can vary depending on the recipe or the restaurant, but all aim to complement the spicy and tangy flavors of the sandwich. While the sandwich mentioned in the question comes with a generic 'slice of cheese' (C), you can customize the type of cheese to suit your preference if you are making the sandwich at home.