Each Voyager spacecraft carries a "postcard" designed to be understandable to any aliens that might someday encounter it. On the "postcard," scientists pinpointed the location of Earth by triangulating it between pulsars. Why did the scientists choose pulsars rather than some other type of star?

A)Pulsars are very bright and therefore easy to find.
B)Several pulsars are located within a dozen light-years of our solar system, making them useful for finding our solar system.
C)We're pretty sure that aliens will have only radio telescopes and not optical telescopes, so they'll have a better chance of seeing pulsars than ordinary stars.
D)Pulsars are easy to identify by their almost perfectly steady periods of pulsation.