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
Diagnostic meathod of choice in contact dermatitis 
Select and explain. 
A. Clinical examination, B. Skin Biopsy, C. Tzank Smear, D. Patch Test
D: Patch Test
Answer: D: Patch Test 
Explanation: D i.e. Patch Test