Final answer:
A five-year-old child with a food allergy is most likely allergic to soy.
Step-by-step explanation:
A five-year-old child named Kimberly who has a food allergy is most likely allergic to soy. Food allergies occur when the immune system reacts to certain substances in food, treating them as harmful invaders. Common food allergies include nuts, eggs, grains, and milk, and soy is among the most common allergens.