In the Search for Planets Around Other Stars,which Possible Line

In the search for planets around other stars,which possible line of evidence has NOT yet been seen?

A) a warped disk of dust and gas around a young star
B) the wavy path of a star through space, as if the star were being tugged by an orbiting planet
C) faint pinpoints of light slowly circling a star
D) cyclic Doppler shift variations in a star's spectrum