Below are some of the factors which could possibly influence the speed of wave propagation. What are the factors which could possibly influence the speed of propagation of light ?

Question

$\begin{array}{1 1} \text{1) nature of the source } \\ \text{2) direction of propagation } \\ \text{3) motion of source and/ or observer} \\ \text{4) Wavelength } \\ \text{5) intensity of source}\end{array}$