Interstellar Matter Obscures Our View of the Disk of the Milky

Interstellar matter obscures our view of the disk of the Milky Way Galaxy:

A) most at radio wavelengths, where hydrogen absorbs radio waves efficiently, and least at optical wavelengths.
B) more at optical wavelengths and less or not at all at infrared and radio wavelengths.
C) very little at any wavelength.
D) more or less equally at all wavelengths, from radio waves to light waves.