If `hat(i)` denotes a unit vector along incident light ray, `hat( r)` a unit vector along refracted ray into a medium of refractive index `mu` and `hat(n)` unit vector normal to boundary of medium directed towards incident medium, then law of refraction is

Options

A. `hati* hatn = mu (hatr* hatn)`
B. `hati xx hatn = mu (hatn xx hatr)`
C. `hat xx hatn = mu(hatr xx hatn)`
D. `mu(hati xx hatn) = hatr xx hatn)`