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: Microbiology
Which of the following is caused by deficiency of complement C3 and C3b? 
Select and explain. 
A. Hereditary angioneurotic edema, B. SLE, C. Severe recurrent pyogenic infection, D. Collagen vascular disease
C: Severe recurrent pyogenic infection
Answer: C: Severe recurrent pyogenic infection 
Explanation: C1 inhibitor deficiency is associated with hereditary angioneurotic oedema. C3 deficiency is associated with severe recurrent pyogenic infection. Deficiency of C1 to C4 is associated with SLE Ref: Textbook of Microbiology by Ananthanarayanan, 6th Editio, Page 108.