One of the factors that misled the herschels into concluding that we are at the universe's center was:
a. hot hydrogen gas in our galaxy's disk, its emission hiding the more distant stars
b. dust that obscures the more distant stars and thereby localizes observations
c. gravitational lensing of light by dark matter, distorting the positions of the stars
d. some "neutron star clusters" that are actually distant galaxies that are distributed uniformly around the sun