This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Dental
A person presented with recurrent swelling on face and lips due to emotional stress, cause is – 
Select and explain. 
A. C1 esterase inhibitor deficiency, B. Allergy, C. Anaphylaxis, D. None of the above
A: C1 esterase inhibitor deficiency
Answer: A: C1 esterase inhibitor deficiency 
Explanation: Recurrent episodes of edema of face & lips after emotional stress suggest the diagnosis of Hereditary Angioneurotic Edema caused by C1 esterase inhibitor deficiency.