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: Skin
All are true regarding hereditary angioedema, except? 
Select and explain. 
A. Dysfunction of enzyme is most common cause, B. Enzyme involved in Cl INH, C. Cl inhibitor targets Hageman factor, D. Complement C4 & C2 decrease
A: Dysfunction of enzyme is most common cause
Answer: A: Dysfunction of enzyme is most common cause 
Explanation: A i.e. Dysfunction of enzyme is most common case