The dark absorption lines on the continous spectrum represents absoprtion of some of the light before the observation of the spectrum.
The continous spectrum of helium represents the star is made up of helium.
The dark absorption lines superimposed on the sontinous spectrum represents the light from the star has passed through a cloud of helium in which helium atoms absorbs the emitted helium light from the star.
Hence, option D is a correct answer.