<prompt> Which of the following is caused by deficiency of complement C3 and C3b?Hereditary angioneurotic edemaSLESevere recurrent pyogenic infectionCollagen vascular disease  <response>: 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. 