This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Papulosquamous disorders, Subject name: Dental
Grattage test is used for- 
Select and explain. 
A. Tinea capitis, B. Lichen planus, C. Pemphigus vulgaris, D. Psoriasis
D: Psoriasis
Answer: D: Psoriasis 
Explanation: Grattage test: scales in a psoriatic plaque can be accentuated by scraping with a glass slide. signe de la tache de bougie: characteristic coherence of scales as if one scratches a wax candle