Electrons of mass m with de Broglie wavelength λ fall on a target in an X-ray tube. The cutoff wavelength λ₀​ of emitted X-rays is given by:
(a) λ₀​=h​/m
(b) λ₀​=h/2m​
(c) λ₀​=h/3m​
(d) λ₀​=2h/m​