Which of the following allergens is found in the Cajun chicken sandwich?

The correct answer is found in the ingredient list of the Cajun chicken sandwich, which typically includes components that may contain sulphites. Sulphites are often used as preservatives in various foods, including sauces and marinades, which are common in many sandwiches. Understanding that sulphites can be present in certain flavorings or dressings that accompany the chicken helps clarify why this allergen is a likely candidate.

Other allergens listed, such as tree nuts, shellfish, and celery, are not typically associated with a Cajun chicken sandwich. Tree nuts and shellfish generally do not feature in this type of dish, while celery is more commonly found in soups or salads rather than specifically in a chicken sandwich. Thus, the presence of sulphites is recognized as the most relevant allergen in the context of the Cajun chicken sandwich.