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: Pathology
Antigen-antibody complex mediated hypersensitivity is - 
Select and explain. 
A. Type -1 hypersensitivity, B. Type -2 hypersensitivity, C. Type -4 hypersensitivity, D. Type -3 hypersensitivity
D: Type -3 hypersensitivity
Answer: D: Type -3 hypersensitivity 
Explanation: a) Type I reactions (immediate hypersensitivity) → Involve immunoglobulin ‘E’(IgE) mediated release of Histamine and other mediators from mast cells and basophils.
b) Type II reactions (Antibody-mediated) → Involve immunoglobulin G or Immunoglobulin M bound to cell surface antigen, with subsequent complement fixation.
c) Type III reactions (Immune complex-mediated) → involve circulating antigen-antibody complexes that deposit in postcapillary venules, with subsequent complement fixation.
d) Type IV reactions (delayed hypersensitivity cell-mediated) → Mediated by T-cells.