What Happens to Light Passing Through Even Thin Clouds of Dust

What happens to light passing through even thin clouds of dust?

A) Even a little can completely block all light, such as the Horsehead Nebula.
B) It dims and reddens the light of all more distant stars.
C) Its motion causes the light of stars beyond to twinkle.
D) The light that passes through them is blueshifted due to the cloud's approach.
E) Its motion causes all light to be redshifted as it passes through these clouds.