Electromagnetic radiation of frequency `n`, wavelength `lambda`, travelling with velocity v in air, enters a glass slab of refractive index `mu`. The frequency, wavelength and velocity of light in the glass slab will be respectively
A. `n/mu, lambda/mu, v/mu`
B. `n, lambda/mu, v/mu`
C. `n, lambda, v/mu`
D. `n/mu, lambda/mu, v`
