Image Quiz: Dermatology-Patchy alopecia in a Chihuahua

This Chihuahua puppy has patchy areas of nonpruritic alopecia on its face and trunk.

Results of cytologic examination of skin scrapings for mites were negative, but a trichogram demonstrated fungal infection of several hair shafts.

Gross and cytologic morphology of the dermatophyte culture are shown below.

What is your diagnosis?

a) Microsporum gypseum infection

b) Trichophyton mentagrophytes infection

c) Microsporum nanum infection

d) Microsporum canis infection