The immune system is responsible for causing the reaction to a food allergen.
The body system that causes the reaction to a food allergen is the immune system. When a person with a food allergy consumes a particular food that their immune system identifies as harmful, it triggers an immune response. The immune system releases antibodies, such as immunoglobulin E (IgE), in an attempt to fight off the perceived threat. This immune response can cause a range of symptoms, including itching, hives, swelling, difficulty breathing, digestive issues, or even a life-threatening reaction called anaphylaxis. So, the correct answer is the immune system.
