The Puzzle About Quasar Spectra, Which Was Finally Solved by Maarten

The puzzle about quasar spectra, which was finally solved by Maarten Schmidt, was

A) that the characteristic pattern of hydrogen spectral lines was seen but at much greater blueshifts than is usual from hydrogen in stellar sources.
B) that the brightnesses of hydrogen lines in the familiar spectral sequence were seen to fluctuate wildly over times of seconds from such a bright and therefore presumably large object.
C) that the characteristic pattern of hydrogen spectral lines was seen but at much greater redshifts than is usual from hydrogen in stellar sources.
D) that a familiar spectral line sequence of hydrogen lines was detected from these starlike objects, but they had intensity ratios between lines radically different from those seen in spectra from nearby stars.