The Fastest Speed at Which We Might Communicate with Another

Multiple Choice

The fastest speed at which we might communicate with another technological civilization among the stars (according to our present understanding of science) is

A) the speed of sound (the natural speed for messages)
B) the speed of light
C) the speed of the Voyager spacecraft (which is typical of our space probes)
D) instantly (as fast as we want) -- if we only knew where they were located
E) the orbital speed of the Earth