This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Dermatitis Erythema, Subject name: Skin
Diagnosis of contact dermatitis is done by - 
Select and explain. 
A. PATCH test, B. Woods lamp, C. Skin biopsy, D. Darrier's sign
A: PATCH test
Answer: A: PATCH test 
Explanation: Ans. is 'a' i.e., PATCH test Diagnosis of Contact dermatitiso Diagnosis of contact dermatitis is made by patch test. Patch test is the only effective means of confirming contact dermatitis. In patch test reading is taken after 48-72 hours to see the signs of delayed hypersensitivity, i.e., induration.