When gneiss is melted, it crystallizes into igneous rock. The correct option among all the options given in the question is option "C". It is also a fact the gneiss does not melt all at once. During the phase of initial melting, gneiss turns into migmatite. The early part of the melted material tend to become granite. So it is a true fact that gneiss tends to convert to an igneous rock on melting.
