Final answer:
Food allergies are most frequently caused by foods such as eggs, peanuts, and milk. These substances may provoke immune responses leading to various symptoms, and in severe cases, can result in anaphylaxis.
Step-by-step explanation:
Food allergies are commonly caused by a variety of foods, some of the most well-known being eggs, peanuts, and milk. These particular foods contain proteins that the immune system mistakenly identifies as harmful, triggering an allergic response. If a person is allergic to these foods, consuming even a small amount can lead to symptoms ranging from mild, such as itching or swelling of the lips and mouth to more severe reactions like trouble breathing or anaphylaxis, which requires immediate medical attention.
Out of the options provided, answer choice 'a. eggs peanuts, and milk' includes the foods that are some of the most common allergens. Grains and shellfish are also highly allergenic and many people are allergic to nuts more broadly, not just peanuts. Thus, care should be taken with these common causes of food allergies.