Let us list some of the factors which could possibly influence the speed of wave propagation : (i) Nature of source (ii) direction of propagation (iii) motion of source and//or observer (iv) wave length (v) intensity of the wave.
On which of these factors, if any does (a) the speed of light in vaccum (b) speed of light in a medium (say glass or water) depend ?

Explanation

(a) The speed of light in vacuum is a universal constant, it is independent of all the factors given above or any other factor. (b) Speed of light in a medium
(i) is independent of the nature of the source. It is determined by the properties of the medium thorugh which light is propagating.
(ii) does not depend on the direction of propagation for an isotropic media.
(iii) is independent of the motion of the source relative to the medium but depeds on the motion of the observer relative to the medium.
(iv) is dependent of the wavelength .
(v) is independent of intensity of light.