The correct answer is A. 308nm.

Note the depigmented patches on the dorsal hand in this patient, which is most consistent with vitiligo. One treatment modality for this condition involves the use of an excimer laser, which directs light with a wavelength of approximately 308nm on the lesions.

365nm is the wavelength of light used in a Wood lamp. 532nm and 1064nm are the wavelengths of Nd:YAG lasers, which are used in multiple skin conditions apart from vitiligo (e.g., nevus of Ota). 595nm is the wavelength of light used by pulsed dye laser, which can be used for rosacea

References:

Alhowaish AK, Dietrich N, Onder M, Fritz K. Effectiveness of a 308-nm excimer
laser in treatment of vitiligo: a review. Lasers Med Sci. 2013;28(3):1035-1041.