Question

if a star is behind a dust cloud, it appears
more blueshifted than it would with no cloud.
brighter at visible wavelengths than it would with no cloud.
more red than it would with no cloud.
fainter at all wavelengths evenly than it would with no cloud.

Explanation:

Dust clouds in space scatter and absorb light. Shorter - wavelength (bluer) light is more affected by scattering than longer - wavelength (redder) light. So, when a star is behind a dust cloud, more of the blue light is removed, making the star appear redder. Also, the dust cloud absorbs some of the star's light, but not evenly across all wavelengths with red light being less affected by absorption and scattering compared to blue light.

Answer:

more red than it would with no cloud.