This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Fungal Infection, Subject name: Skin
Patient suffering from lesions over axilla, groin and trunk. Lesions show central clearing with surrounding papulovesicular margin progressively increasing at borders. Which will be the preferred investigation among the following? 
Select and explain. 
A. Wood's lamp examination, B. 10% KOH mount, C. Skin biopsy, D. Patch testing
B: 10% KOH mount
Answer: B: 10% KOH mount 
Explanation: Ans. b. 10% KOH mountExplanation: Central clearing is associated with tinea corporis (dermatophytic fungal infection). So, answer will be KOH mount.