The Discovery of the Peculiar Galaxy Cygnus a Was a Surprise

The discovery of the peculiar galaxy Cygnus A was a surprise to astronomers because

A) the redshift of its radio wavelength signal was as high as anything measured up to that time.
B) it was first discovered at X-ray wavelengths and detected at optical and radio wavelengths only some time later.
C) it was so bright at optical wavelengths that no one expected it to be a galaxy.
D) it was very faint at visible wavelengths but extremely bright at radio wavelengths.