If `epsi_(0)` and `mu_(0)` are respectively, the electric permittivity and the magnetic permeability of free space, `epsi` and `mu` the corresponding quantities in a medium, the refractive index of the medium is
A. `sqrt((muepsi)/(mu_(0)epsi_(0)))`
B. `(muepsi)/(mu_(0)epsi_(0))`
C. `sqrt((mu_(0)epsi_(0))/(muepsi))`
D. `sqrt((mumu_(0))/(epsiepsi_(0)))`