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
Patch test is done to document aEUR' 
Select and explain. 
A. Type I hypersensitivity, B. Delayed type hypersensitivity, C. Autoimtnune disease, D. Immunocomplex deposition
B: Delayed type hypersensitivity
Answer: B: Delayed type hypersensitivity 
Explanation: Delayed type of hypersensitivity Patch test Patch test is done to detect contact dermatitis. Patch test detects type IV hypersensitivity (delayed) reaction to exogenous allergens. Patch test is a very simple technique which consists of applying the suspected agent or its chemical ingredients in specified concentration on normal looking skin on the back of the patient under separate patches for 48 hours and looking if this application produces dermatitis on the area,