<prompt> A 60year old male presented with discolouration, thickening and tunneling of 2 fingernails and one toe nail. Which of the following will clinch the diagnosis at the earliest?Woods lamp examinationKOH mountSlit smear split skin smearGram stain  <response>: Discolouring and tunneling of the fingernails suggests onychomycosis Tinea unguiumOnychomycosis refers to nail infections caused by any fungus, including yeasts and nondermatophyte molds.KOH mount is used for fungal infections. 