Final answer:
The proper response to a guest's allergen notification is to alert the kitchen staff and provide alternative menu options. Ignoring the information or asking the guest to leave are not appropriate actions. Offering a complimentary dessert is also unsuitable and potentially dangerous.
Step-by-step explanation:
When a guest informs a restaurant of an allergy, the correct course of action is to notify the kitchen staff immediately about the allergy. It is essential for the server to communicate precise information about the guest's allergy to the kitchen team to prevent any cross-contamination or accidental inclusion of the allergen in the dish. Furthermore, the server should present the guest with alternative menu options that are safe for them to consume, if available. Offering a complimentary dessert is not a standard response and could pose additional risks if the dessert contains allergens. Lastly, it would be highly inappropriate to ignore the guest's concern or ask them to leave as it could lead to serious health repercussions and damage the restaurant's reputation.