Which is not correct statement about the function of flux in brazing?

 a) To avoid thermal distortion and cracking
 b) To dissolve surface oxide coatings which have formed prior to brazing
 c) To prevent oxides from forming during the brazing operation on both the base metal and the brazing material
 d) To facilitate the wetting process by reducing the viscosity of the melt

ISRO Scientist-2010

To avoid thermal distortion and cracking.