What might happen to an individual with a shellfish allergy who consumes clam juice unknowingly?

An individual with a shellfish allergy who consumes clam juice unknowingly may experience tightening in the throat due to an allergic reaction. Shellfish allergies can provoke a range of symptoms, the most serious of which is anaphylaxis, a severe and potentially life-threatening reaction. This can lead to swelling in the throat and airways, making it difficult to breathe. The tightening sensation is often a direct response to the body releasing histamines, which occur as part of the immune system's defense against what it mistakenly identifies as a harmful substance.

The other potential options regarding feeling fine or experiencing minor stomach discomfort do not accurately represent the typical response associated with a shellfish allergy. Furthermore, experiencing a sugar spike is unrelated to allergic reactions and is more commonly associated with carbohydrate intake and diabetes management. Therefore, the correct understanding of allergic reactions, particularly in the context of shellfish, emphasizes the seriousness of the symptoms that can arise, such as tightening in the throat.