This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immunology Pa 1 (Immune Response, Antigen-Antibody Reactions, Hypersensitivity, Structure of Immune System, Immunodeficiency Disorders), Subject name: Microbiology
Type III reaction is- 
Select and explain. 
A. Antibody mediated, B. Immune complex mediated, C. Cell mediated, D. None
B: Immune complex mediated
Answer: B: Immune complex mediated 
Explanation: Option 2 Type-III hypersensitivity reactions are as a result of excess formation of immune complexes (Ag-Ab complexes) which initiate an inflammatory response through activation of complement system leading to tissue injury: Localized or Ahus reaction Generalized or Systemic type III Reactions, e.g. Serum sickness. Option 1 Type-I: IgE-mediated degranulation of basophils or mast cells. Type-II: IgG Antibodies against cell surface antigen, causing damage by ADCC or complement activation. Option 3 Type-IV hypersensitivity:- It is delayed type (occurs after 48-72 hours of antigen exposure) Cell mediated: Characteristic cells called TDTH cells are the principal mediators