Astronomers Have Found Large Quantities of Cold, Neutral Hydrogen Gas

Astronomers have found large quantities of cold, neutral hydrogen gas in our galaxy. How is this gas distributed?

A) it is located only near stars, and not in the large empty spaces between them
B) it is found mostly in a flat layer extending throughout the disk of our galaxy
C) it is found in a spherical distribution about 100 LY in size, centered on the Sun
D) it is found only in the outer regions of the galaxy, where we are, and not in the central areas
E) we don't know its distribution, since such cold hydrogen cannot be observed with the techniques we have at our disposal today