Which of the following is a symptom of an allergy?

• A. Sneezing only
• B. Swelling of the throat and mouth
• C. Headache due to dehydration
• D. Hair loss

Answer: (B)

Allergic reactions often involve swelling of tissues where the allergen has come into contact or entered the body. Swelling of the throat and mouth is a clear sign because it shows mucous membranes reacting and can quickly threaten the airway, making it a potentially life‑threatening emergency if it progresses. The other options don’t fit as reliably: sneezing can occur with allergies but “sneezing only” isn’t a definite allergy symptom and doesn’t indicate airway involvement; a headache from dehydration isn’t related to an allergic response; hair loss isn’t a typical reaction to allergies. In practice, noticing throat or mouth swelling should prompt urgent attention and possible emergency action.