During the filling process of a given sand mould cavity bymolten metal through a horizontal runner..

During the filling process of a given sand mould cavity bymolten metal through a horizontal runner of circular crosssectionthe frictional head loss of the molten metal in therunner will increase with the(a) increase in runner diameter(b) decrease in internal surface roughness of runner(c) decrease in length of runner(d) increase in average velocity of molten metal