Which sauce is commonly used on Taco Bell's nachos?

The sauce commonly used on Taco Bell's nachos is nacho cheese sauce. This velvety and creamy cheese sauce is specifically designed to complement the crunchy tortilla chips, providing a rich and flavorful experience that enhances the overall enjoyment of the dish. Nacho cheese sauce is a staple in many nacho dishes, particularly at fast-food restaurants, due to its gooey texture and cheesy flavor that appeals to a wide range of customers.

While ranch dressing, guacamole, and barbecue sauce are all popular condiments, they are not the traditional or primary choice for nachos at Taco Bell. Ranch dressing is typically used with salads or as a dip, guacamole usually accompanies burritos or tacos, and barbecue sauce is more commonly associated with meat dishes or sandwiches. Thus, nacho cheese sauce stands out as the quintessential topping for nachos, making it the correct answer in this scenario.