If Interstellar Dust Obscures Astronomers' View of Distant Regions of Space

Multiple Choice

If interstellar dust obscures astronomers' view of distant regions of space at optical wavelengths, which of these statements is true?

A) The obscuration is very clumpy and random over the whole sky; the individual absorbing dust clouds show no preference for one particular direction or plane.
B) The obscuration is roughly uniform over the whole sky.
C) The obscuration is the least in the plane of the Milky Way Galaxy and is strongest when one looks out into the galactic halo, at right angles in this plane.
D) The obscuration is severe only in the plane of the Milky Way Galaxy.