In the context of propagation delay if d is the length of the physical link, and s is the propagation speed $($approximately $2$x$1018$ m$/$s$).$ what is the propagation delay for a physical link of $500$ meters?O a$.0\mathrm{.}5$ microsecondsO b$.1\mathrm{.}0$ microsecondsO c$.2\mathrm{.}0$ microsecondsO d$.2\mathrm{.}5$ microseconds whats the right answer?