In solar spectrum when looking for sodium, it would be a (n) absorption line. A gas of hydrogen will produce absorption spectrum it is between teloscope and spectrograph and a continuum light source. An emission line is spectrum is viewed from a different angle.
We are tasked to fill in the right term which describes the blank space provided in the question if you were looking for sodium in the solar spectrum, it would be an absorption line. The line was originally seen as a dark light which in turn realized by Joseph Fraunhofer that it is an absorption line which he called it Fraunhofer lines.
